Relationships with female characters is actually something I think that more games could benefit from. Some games that suck out for me on this were Shenmue from Dreamcast, Grandia II, and FFVI, but they used it more to help build atmosphere and drive an interesting story. I can't really recall the last time a non-dating sim oriented game attempted to take a good stab at the whole relationship building... Harvest Moon? Uhm... in The Witcher you can hit on girls to try to get the protagonist layed, and take actions that strengthen the relationship he as with specific key characters...
So, I guess the only game I can think of that really tried any sort of female relationship related gameplay that I can think of, from recent titles... is The Witcher?
I for one, think that hitting on girls is fun. Whether its in a game, or in real life. I'd like to see more RPGs where your actions effect the way female NPC interact with the character in a romantic way... It can lead to all kinds of amusing gameplay. Or maybe I'm just a perv, but whatever.