I did not watch Northern Exposure to the end; what ever happened with Joel and Maggie?
I thought it was pretty clear that it did happen.
Suzumiya-san and Kyon-kun in Haruhi Suzumiya. We know Kyon will get nowhere with Asahina-san, since her future self tells him, and Nagato-san is just a humanoid interface, with or without her glasses, but Suzumiya always seems like a possibility.
Am I being whooshed? I never thought Buddy and Sally had anything going on! Buddy was always married to Pickles. Sally had her boyfriend Herman for a while, a unconsumated romance with the deli owner (can’t remember his name, but he was played by Sid Melton), and a failed affair with a TV comic who only loved her for her jokes.
I always thought Joey & Phoebe would ultimately hook up, since Ross & Rachel did and Monica & Chandler did; if for no other reason than to complete the trifecta.
How about Scully and Mulder on the X-Files? The writers seemed to play around with an attraction between the two characters, but eventually they did settle into a definitely-platonic relationship.
Spongebob and Patrick.
Joel & Maggie DID indeed ‘do it’ - but it was a few months before Fleischman left Cicely. Maggie blamed it on whatever weird quasi-Native American mystical mojo was happening in that week’s episode (and she was still going out with ‘bubble boy’ Anthony Edwards at the time.) They got engaged to be married just shortly before Joel took off for the deeper wilderlands. So, it’s a hard call on that one. They had sex, but with no real intimacy, and aborted their plans to really hook up.
As for Joey & Phoebe on “Friends”, the storyline briefly suggest that would happen, but it was scrapped after the producers realized that Matt LeBlanc & Lisa Kudrow had zero chemistry as lovers. And anyway, LeBlanc signed on to do a solo spin-off show (remember that?) Kudrow went on to do a much better (but unfortunately just as short-lived) non-spinoff series.
Wonder Years, Kevin and Winnie.
I would say they were out of “definitely platonic” by S7.
They had a child together. There were several episodes where a sexual relationship was implied. The first time Mulder sees her in the series finale he kisses her like she’s the love of his life and he never thought he would see her again. At the end of the series, they essentially run away together. And also they’re very clearly a committed couple in the recent film.
Marlin & Dory 
Dave and Lisa from NewsRadio were a couple for the greater part of the series, but ultimately broke up stayed broken up. Lisa wound up married to the evil Johnny Johnson.
John Steed and Mrs. Peel on “The Avengers”
They did hook-up at the end of one episode.
I don’t think I ever actually saw the last episode but I always kind of assumed that they’d end up together eventually.
What about Frye and Lela from Futurama?
I think most “West Wing” fans expected Josh Lyman (Bradley Whitford) to end up with Donna (Janel Moloney), but it never happened.
Yes it did. I recall an interview in which Bradley Whitford pretended to complain about having to spend all day shooting scenes in which he was either making out with Janel Moloney or watching her lounge around a bedroom naked.
What? There was romantic tension between them? I totally missed that.
Besides, Buddy had a wife, and Sally had a boyfriend. No way they could have hooked up back then.
Luke and Leia.
How about Dr. House & Dr. Cuddy? I know it seems like they will, but they really haven’t (except for one kiss, and that wierd dream House had.)
Or even House & Wilson?