The Persona games require quite a bit of work on your part as well. Though the romance is a side aspect of those games.

I'm surprised nobody mentioned Temple of Elemental Evil yet. You can marry several characters there, but what's most distinctive (especially considering that the game is 10 years old) you can have a gay marriage there. I think it was pretty controversial back in 2003

Lol, I remember that, the gay NPC was a pirate too :P

So, no mute girl?

(Sorry, I really really really had to :D).

She's deaf and mute :P

Yeah, but all those love-subplots were pretty lame in ToEE. At the moment I only remember three of them but:
- The pirate was very clingy
- One woman was extremely possessive
- But the most creepy person you could marry was a girl that you could woo by telling her your stories. You also had to arrange a marriage for her older sister before marrying her. So what was so creepy? I don't know who voiced her but she sounded like thirteen years old girl and that was really strange to marry her. Not that I ever did but still...

Oh wait, you could get a slave lover in Nulb, no? It makes it four but anyway, their personalities were very bland

I chose the blind chick for multiple reasons :P

If you don't have anything against manga-like visual novels, I really recommend you to try Katawa Shoujo - it's free!

http://www.katawa-shoujo.com/

This deserves every upvote in the world.

has nobody said Fable 3?!
not to mention it was the first game to ever include same sex r/s!

I think someone said Fable series but, wait, has no-one said, Mass Effect series yet, they were kinda famous for it!
I think, when it went through each character one by one at the end of Planescape Torment, you could find out then, and only then, when it was too late, if one or more female characters were in love with you!

Nobody's mentioned Arcanum?

It has prostitution (if your character is female, you can even become one yourself as part of a side story), bestiality (if you're too cheap to spring for a hooker), and one of the elven followers you can add to your party can fall in love with you (if your character is of a compatible species: human, elf or half-elf).

All this sex talk is damaging y'alls short term memory. Mass Effect is in the first post. :)

Just remembered another game from the old DOS days - Romantic Encounters at the Dome.

While we're digging up the old stuff, the Infocom title Leather Goddesses of Phobos had some pretty good romantic content too.

So does Divine Divinity now that I think about it. It also has a marriage quest if your character is female but it can be a real pain to finish and not really worth much exp.

Oh yeah, duh!
Talk of text adventures reminds me of Soft Porn Adventrure, which was remade into Leisure Suit Larry and now I'm thinking that no-one has mentioned Larry Laffer yet but you'll probably point out that ts in the second post down or something :P