I think it's possible for any of them to be in a relationship, and if they're not, it would be by choice. Usagi would NEVER want for any of them to have to give up hope of finding love for her. Because so much emphasis is placed on boys for the Inner Senshi, I'm going to focus on that, but I think it's possible that any of them could be bisexual.

Ami - There's really nothing that says for certain she won't have someone. She showed at least some interest in boys in both the anime and the manga. She and Ryo obviously had feelings for each other. I think they probably would have kept seeing each other. After that, she could have a boyfriend later on, maybe meet up with him again, or someone else. Maybe she'll get married, maybe not. Maybe she'll just be married for a little while.

Rei - In the manga, Rei seems to show some attraction to boys. For the most part, though, she doesn't trust men, and she certainly doesn't need them. In both the manga and PGSM, she clearly has strong feelings for Minako. Whether these feelings are romantic or not are up to interpretation. But saying she doesn't trust or need men does not mean she's not romantically interested in them. And even if she's not, it's not impossible that she ends up with a woman. In the anime, she is very clearly interested in boys, as much as Makoto and Minako. I think it's possible she could end up with Yuuichirou if he grows up a little, but I agree with Emerald Knight that Rei would rather be with someone who has more confidence in himself. 

Minako - The tough one! It's true that Kaitou Ace told her that she was destined to never be loved in return. But he could have been lying, hitting her where he knew it would really hurt. Or he could have simply meant that she would always choose Usagi over anyone else. That doesn't mean she couldn't love someone else. That's why I think that Kunzite or Rei would be a good match for her. It would have to be someone who understands that they can never be number one in her life. In Rei's case, she would also have to always choose Usagi over Minako. But that would be fine for both of them. As for the anime, there's really nothing to indicate that Minako can't find love.

Makoto - Makoto is the one I really think will find someone. She is the one who dreams of being a bride more than any of the other senshi, except for Usagi (who has someone already). Like with the others, I think Mako could reconcile love and duty, as long as the other person understood what her first priority must always be.

Setsuna - I don't know if she necessarily wants romantic love as much as the Inner Senshi. She seemed pretty content with her new life. If she was in love with King Endymion, I don't think it passed over into her next life. I think it probably came from the fact that she saw so few people at her post, and out of all of them, Endymion was the only man.

Hotaru, I think, at least in the Infinity arc/S season, had a (possibly unrequited) love for Chibiusa. She was, after all, the only friend she had. Like Rei and Minako, it's hard to say whether or not their feelings for each other were anything more than strong friendship. She might have a crush on Chibiusa in the Dream and Stars arcs, too, although I think that will fade over time, especially once Chibiusa's born, because it would be really awkward to be in love with her then.

I agree that some of the girls could be bisexual, but even so, I'm not fan of Senshi/Senshi pairings.
I also headcanon Ami as keeping in touch with Ryo and meeting him sometimes.
I don't see Rei as needing someone confident, she is confident enough for both. IMO, she will need someone reliable and Yuuichiro is. He can take care of shrine and grandpa, while Rei would develop her international success. Plus she seems to hava affection for him in anime - it may be platonic, but it may not.
And Usagi definitively wants her friends to find the one - especially in anime, but manga also mentions it a few times. I love that trait of her.
I'd love new anime to feature a relationship of Senshi and regular guy.

Rachael wrote:

I think it's possible for any of them to be in a relationship, and if they're not, it would be by choice. Usagi would NEVER want for any of them to have to give up hope of finding love for her. Because so much emphasis is placed on boys for the Inner Senshi, I'm going to focus on that, but I think it's possible that any of them could be bisexual.

[....]

Setsuna - I don't know if she necessarily wants romantic love as much as the Inner Senshi. She seemed pretty content with her new life. If she was in love with King Endymion, I don't think it passed over into her next life. I think it probably came from the fact that she saw so few people at her post, and out of all of them, Endymion was the only man.

Usagi is the most sweetest person ever. If her friends were to find love somehow, she wouldn't be againist. Quite the opposite: She would do anything at her might to see that work. It's her nature. So, if the senshi decides to be alone or single or whatever, I think it would be by their own decision.

Setsuna: I totally agree with Rachel. With so much time at the Gates, she didn't see many people. Endymion was the only man she saw and interact while standing at her post. And let's say that Mamoru/Endymion is a really atractive (specially in manga, when it's clear Pluto has something for him) and oh, many people during the series is attracted to him. Even his future daughter has a crush at his past self (let's not get into it). So, her love for him is kinda natural. And she is aware it's impossible, because he is and always will be in love for Serenity. Besides she loves Serenity too much to do such a thing like have something with Endymion. 
When she died and Serenity re-incarnates Setsuna at 20th century, I don't feel she was in a unriquited love for Mamoru, so maybe it's something that died with her, and besides she retains her personally she changes (Chibiusa says she is different, that Pluto looks more strong and confident), so this unrequiered love died with her 1st life.
And how she'll have a relationship at 20th century, with her duties at the Gates of Time remains? "Hey, love 
I'll be back soon, but I'll have to check at the Gates but I'll be in time for dinner". I don't see that happening. She made a family with the outers and that's it.

The series ends when they are just 16. Not everyone finds their destined one with 14, like Usagi or 15 like Uranus&Neptune - So, to the point when Crystal Tokyo rises or Usagi gets married (with 22, I think) they have a lot of time to find someone.

Besides Naoko-sensei wanted the rest of them to find love, as we see at draw where the 4 inners are paired with the shittenou. And we also have paralel sailor moon as tip. And there is also a picture where all the senshi, even Haruka, is dressed as a bride.
But also there is the fact that her love for UsagiX someone. What would they choose? Each side that they would choose would made them feel guilty for the other that wasn't choosen.
Let's put a situation like we see at future Crystal Tokyo at the Black Moon attack: Everbody in the city dies and they run to protect the palace and Serenity. At the anime we see them as the last at palace's protection, since the king is coma somewhere unable to protect NQS while she is at crystal coffin. If the have a family, let's say a husband, how would they feel leave them to protect Usagi and see this person die outside?

Haruka and Michiru are together because they share the same path. And they both know their Princess is the priority, even above their love for each other. They put their misson and responsibity with Serenity above everything, their own lives and their love. It wouldn't have a conflict or guilty for choosing Serenity/Usagi which the love above all. But I do believe that if the mission is accomplised and Serenity is safe, if one had died in the process, the other would follow soon after so they could be together.

As for Hotaru...She is a kid. Everytime she uses her power, her last powerful attack, she dies and returns as a baby. It's hard having a relationship when your ages changes drastically, huh? And I think I read somewhere (Wiki?) that in the future she is Chibiusa's guardian, so she didn't aged?
Besides she is a senshi that shouldn't have been summoned. She is meant to be alone.

Besides love doesn't always need to mean romance or a boyfriend. They all love Usagi, purely, but it doesn't mean want to date her. They love each other as friends, they love their princess and their planet. So, I think they can have happy and satisfactory lives just with this.

Cerechan wrote:

I know this is very random and dumb but it just kind of pisses me off that the senshi are so dedicated to Usagi. I mean it just seems like to me that she's always needing someone to protect her and everyone is always dying for her and I understand because she's the pure epitome of good which is so cliche. I guess. Just wish their senshi duties would one day and everyone could be normal. Sorry just my rant.

Agreed. How can someone that weak can protect the princess? In manga even that Sailor Moon is really powerful, all the senshi can handle a opponent and kill him/her in battle. Even Tuxedo is powerful enough to join a battle for himself. They combine ppowers and such, they don't need Sailor Moon to finish every bad guy. >.<

I dont think it is fair, everyone deserves a chance at love.

Usagi would never purposely limit the girls' chances at love, but it's hard to find time for a relationship. Between school, family stuff, and saving the world over and over again a relationship would be almost impossible. 

I think if things cooled down after the Stars arc than they may have found time to date, but if there was a new enemy than who knows.

Also, any partners they find would be put in a huge amount of danger. Heck, Mamoru has powers and he still gets targeted all the time.

Is it fair? Nope. Is it very possibly a reality of their jobs? Yup

It isn't really fair. Even though it would make the series way too complicated to give every Senshi a lover, at the very least Mako and Minako could have found love.

I don't really think it's about fairness at all either. If none of the senshi found a partner beyond Uranus and Neptune, I don't think it would be because they are destined to be alone. Some may simply realize that they don't want a relationship after a while, or they'd get a relationship, and it would end later for a myriad of reasons. The senshi are really focused on their jobs as guardians, and since they're nearly immortal in Crystal Tokyo, it's possible for them to get a partner, live a lifetime with them, and then watch them die. I could see why they might avoid a romance after too many of those...

For all we know, there were offscreen romances we just didn't see between the end of the Stars arc and the far future, and by Chibiusa's time, the senshi didn't have partners then. Or you could go another way and say the senshi paired off with each other for company. There's a lot of possibilities.

I haven't seen anyone bring up this argument yet, so here it goes.

I've always seen the other sailor soldiers as more of religious sisters who live their lives in devotion to Sailor Moon. For those who aren't aware, at least in Catholicism, sisters are, in essence, married to Jesus Christ. They devote their lives to Him as a wife would toward a husband. I've always seen the other girls' relationship toward Sailor Moon as being just this. They respect and admire her so much that nothing overpowers it. In my own opinion, Sailor Uranus and Sailor Neptune have always been pictured as the less aligned partially due to their relationship toward each other (and why they're not as close in the manga as they are in the anime).

So is it fair that the other characters don't find love? Well, yes, because they've chosen it for themselves.

Yes, I got that vibe from them too! Not like an exact reference to nuns, but a similar circumstance. It may have taken each senshi a while to explore their romance options, but they eventually decided to just place Serenity as highest priority.

The SM senshi are strong, independent and content women focused on their lives, school studies and commitment as superheroines to save the day, Love is the last thing on their priority lists. Honestly, they don't need a man to satisfy them, romance will come someday when they are ready to pursue a BF or GF. Rei is more concerned with her religious profession (she's a priestess) and she choses not to deal with men (from what I know of Rei's personality), while Minako learns love has to wait (she's desperate) and needs to understand having a successful romantic relationship.

The only senshi relationship comes to mind is Haruka (Uranus) + Michiru (Neptune) as they have a true romantic bond.  I expect Ami and Makoto to have a BF each who's willing to accept the way they are. Personally, I can relate to a smart genius-type or can date a taller, bigger kind of woman. And Usagi is definitely in love with Mamoru, the logical fairy-tale match made in heaven...though Usagi and Mamoru can get into arguments, disagreements and can offend each other sometimes (ROFL). And Setsuna and Hotaru are the least likely to find a man out of the senshi.

I honestly can't see Setsuna being interested in men. Considering how she's been guarding the door, traveled through different points in time and all. Besides, I always got the feeling that she had this one sided crush on the King.

I get argument about Setsuna, but I don't know about Hotaru - she is very young and would have plenty of opportunities.

And these arguments that senshi are strong, independent women seem kinda iffy - wanting romance, needing romance, being in romance doesn't take away one's strength and independence. Similarly, placing Serenity at top priority, when she can enjoy her Miracle Romance isn't totally fair...

I think it's fair if they chose to do it, because I honestly can't see Serenity barring anyone from their love pursuits. So maybe they found love off screen if they wanted it, and Crystal Tokyo is just showing what they did afterwards.