Are there?

That depends what you specifically mean, but you can at least have casual sex with certain NPCs (not prostitution, I mean).

There's a lot of casual sex, if that's what you mean. Generally depends on your "personality" - but if it's not high enough, then getting high usually helps... ;)

Sometimes depends on other stats - depends on the target of affection. And those other stats generally have ways to raise them temporarily too (I think I ended up scoring while high and drunk quite a lot in this game...).

There's none of that stuff between you and your party members AFAIK - which is probably a good thing, since who wants their lover/partner hanging around all the time?

Especially while playing a single-player RPG.