Something I really hated was the Aerie romance in Baldur's Gate 2. I've never managed to complete that, because Aerie is such an aggravating character with her clinginess, insecurity and "innocent" sweetness.
The other romances in that game are far from ideal either, but a lot more bearable and even somewhat interesting (I even liked the Anomen romance for female characters).
iirc only other game with romances (apart from the Witcher 1 where I opted for Triss) I've played and completed was the original Kotor. Bastila was kind of annoying as well, but not nearly on the same level as Aerie.

The title of the thread says "What's your favourite love scene in a video game?", not sex scene...

Paul's moments with Chani in Dune were fine as the rest of the game.

The X-rated Skyrim and Fallout mods. /joking

I like seeing my Shep romance Garrus. In my first playthrough of ME1, I didn't have a romance partner. I unwittingly kept Garrus in my party, and when I realized this, I nick-named him 'lover boy'. When I got around to ME2 is when I decided to go for the romance. I usually don't care for romances in games, but that's the one I like the most.

I tend to find them super awkward because graphics aren't "there yet," but the ones in Mass Effect 1 were alright because they were quick and dark flashes for the most part.

I loved the tension between Fallen From Grace and The Nameless One in PS:T (if you chose the appropriate dialogue options). Of course this "romance" can never come to fruition (adding to the bittersweet feeling).

Coming from the books I really did like how they portrayed the relationship between Geralt and Yennefer in Witcher 3 (if you choose Yen). Sex scenes aside it's very clear how they deeply care for each other. There is not one favourite "scene" for me, just some really nice interactions on the side ("You smell nice on this funeral...").
And for those who haven't read the books (and can't handle a woman like Yen) there's also Triss of course... ;-)

The story with Shani in Hearts of Stone is also very nice, although I wouldn't count that as "love", it's more like friendship plus.

I never saw that as anything romantic tbh.
There's some romance with Annah, iirc she even kisses TNO at some point. But yes, quite bittersweet.

Well you can kiss Grace too... with the expected result. ;-)

You die? (not that this is bad in Planescape Torment...).
Have to admit I've forgotten most of such details about the game. But somehow Fall-from-Grace never made such a deep impression on me anyway like some of the other characters (Morte, Dakkon, Annah). iirc you acquire her fairly late in the game anyway.

Yup :-)

Yes, I really have to replay it again some of these days. IIRC it wasn't so late I got her, and she always kind of stuck in my memory... but Dakkon was probably my favourite party member - tons of amazing dialogue...

But you get respawned? Since he is Immortal

Also it's sad you can't get into her diary

I like it when you get through the end stage on Alley Cat and the two cats make that really loud smooching noise.

[spoiler]
The unanswered and sad lovetriangle between Fatima, Sly Boots and what'shername (Stilletto Anyway after looking it up on Wikipedia) in Anachronox.
[/spoiler]

[spoiler]
The love triangle between Blair, Flint and Rachel, which plays out really funny as you can choose either one to the dismay of the one you didn't choose and you could even choose none which would made your life really hard on board the TCS Victory. The game in question is Wing Commander III by the way.
[/spoiler]

And for the rest, while I'm not a big fan of jrpg's, lovestories and character building is generally better done in Japanese games than in western made games (imo of course).
I also like the innocent attraction between the two characters in ICO for example.

From what I recall, she gets pretty fiery and passionately claws into TNO's back, tiefling style. XD

Haha. I unsuccesfully tried to find some footage of it, but I stumbled upon this freeware homage/remake, in case anyone's interested. It even supports multiplayer.

. Does it get any more romantic than this scene (see attached picture)? ;P

There was a time when I had only 2 games installed on IBM PC compliant computer: Alley Cat and Paratrooper. Those were the times.

Alley Cat Remeow Edition looks pretty awesome!
https://www.youtube.com/watch?v=WIm6oRhyDrM

phoebe's version of ally cat might be the best there is