From the title there are some series that the main or supporting characters are supposed to be couples but never came to be. For example: Sesshomaru and Rin from Inuyasha did have a mutual relationship but never came to be. Are there any more couples that never came to be?

Well she was a little child thou
i havnt seen inuyasha in a long time, so i dont know what happends really

hmmm sora and tai from digimon i guess

digimon 2 we have davis/david or what ever his name is, he liked that girl with the cat

digimon 3, the main char and that girl he liked(jen or somthing)

digimon 4, the blue guy and that pink one

lol

in DBZ yamchu and chichi(there was some stuff when they were little i think)
kurrurin(or rather said the bald guy) and some blue haird girl called somtihng(but then he got # 18 later)

full metal alchemist, ed and winry

hmmm i'm not so sure if this is the right thing i was supposed to be talking/saying about thou <_<

Ramna 1/2 - Despite the huge amount of crap everyone went through, surprisingly Ranma and Akane never hooked up in the end. I was very sad.

Escaflowne - I sort of feel like Hitomi and Van never really hooked up. It was obvious that loved each other, but at the very least they could've kissed at least!

Trigun - Vash and Meryl. This was a couple I really wanted to see get together, but I'm also glad they didn't since Vash obviousy had a lot to deal with before he could ever hope to have a relationship.

Spike and Jullia from Cowboy Bebop. They were together once, but not in the series.

SPOILER WARNING

They were sort of a couple for about half of one of the last episodes. Until Julia got iced. That kind of puts a stop to relationships.

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Sesshomaru and Rin from Inuyasha did have a mutual relationship but never came to be.

Dude that's disgusting. Thats like child molestation.

SPOILER WARNING

use the spoiler tag.

Spiral had a couple.

SPOILER (click to view)

Hiyono and Ayumu were obviously girlfriend and boyfriend by the end of the series, but they never did anything with it. The same with Ryoko and Kyosuke.

Parn and Deedlet from Record of Lodoss war also had an unknown ending to their relationship.

Lostsamurai

Sesshomaru and Rin from Inuyasha did have a mutual relationship but never came to be.

Dude that's disgusting. Thats like child molestation.

SPOILER WARNING

use the spoiler tag.

Spiral had a couple.

SPOILER (click to view)

Hiyono and Ayumu were obviously girlfriend and boyfriend by the end of the series, but they never did anything with it. The same with Ryoko and Kyosuke.

Parn and Deedlet from Record of Lodoss war also had an unknown ending to their relationship.

The only problem is, I detest being forced to click on the little spoiler thing to see more content, so I just put my spoiler warnings in like that. Most people have already seen bebop by now anyway ;- ).

To each his own.

Rurouni Kenshin: Megumi and Sanosuke! =p

MAYBE Elfen Lied anime

SPOILER (click to view)

Kouta and Lucy: Who knows if she really died? Who knows positively if she was at the door or not? Most likely she was. But they did have their romantic moment.

FMA --> Edward and Winry. Pretty sad too..:(

Mizuno Youko and Satou Sei from Maria-sama ga Miteru.
Jessie Gurtland and Ayla Veferascca Roznovsky from Battle Athletes Victory
Mizuhara Makoto and Jinnai Nanami from El-Hazard

Has anyone seen utena?

SPOILER (click to view)

does that ending count as the two coming together? possibly the movie but im not sure about the series

hiro4

has anyone seen utena?

SPOILER (click to view)

does that ending count as the two coming together? possibly the movie but im not sure about the series

SPOILER (click to view)

they're together at the end of the series. Anthy left Ohtori Academy to search for Utena

Naruto and sakura OR naruto and hinata

Kimi ga: Haruka & Takeyuki (or how he was called, always forgets his name XD)
Elfen Lied: Lucy & Kouta
Ranma and Akane (this is creepy xD)
[Ash & Misty](?)

Dragon Ball: Yamcha and Buruma (Bulma)
NGE: Misato and Kaji
Ranma 1/2: Ranma and Akane (Ranma and Akane not quite getting together is actually kind of poetic for the author. Godai and Kyoko [Maisson Ikkoku] got together, Ataru and Lum [Urusai Yatsura] never did. Ranma and Akane are close, but not quite.)
Saber Rider and the Star Sheriffs: Saber and April (It looks like April later went on to be with Fireball)
Bubblegum Crisis: Leon and Priss (In the OAV, they alluded to but never got together. Did they get together in the TV series?)
Space Battleship Yamato / Starblazers: Kodai and Yuki / Wildstar and Nova (Did they actually ever get together?)

Someone mentioned Mizuhara Makoto and Jinnai Nanami, from El hazard. This may be true in the TV series, but in the original (and superior) OAV series, Makoto and Ifurita were definitively together.

Lina Inverse and Goury from Slayers.

Though I must admit that I haven't watched all Seasons (yet), but I strongly doubt it.