I agree with *~Dagger Trepe~*: Squall is with Rinoa for a reason.

Squall/Selphie probably wouldn't work out; she's too...independent for him. I hate to say this, but I think that Squall is a bit of a co-dependent (i.e. a needy person who needs to be needed). That's one of the reasons why Rinoa is perfect for him: he's starved for love and affection...which are things that Rinoa is willing and able to lavish on him - and she's rather clingy, herself. Rinoa seems to be the kind of girl who thrives in romantic relationships, whereas Selphie doesn't really seem to be interested in boys in any serious way - beyond innocent flirtations and crushes on much older men *coughLagunacough*. Selphie seems to be enjoying her teenage life as a single girl. Good for her!!!

As for Squall/Quistis...it wouldn't work out. Actually, I should say, "it didn't work out". Quistis knew Squall for 16 years before Rinoa arrived on the scene - so she had plenty of chances. Clearly, there is nothing between them. And whatever little there might be between them is entirely one-sided.

I think that covers all of the eligible young women in the game....