Yes. Jaheria, Viconia, Aerie, Anomen OR Kelsey (not both), and Sola.
Tashia can also be added if you download a certain patch.
If you have the flirt packs, though, I _THINK_ Jaheria and Aerie will break up with you if you don't break up with Sola. At least, there is dialog for it. I'm not sure if it works, but it's there.
And Anomen and Kelsey will force you to choose between them, although any other romances will still carry on. There IS a patch in the Kelsey romance that will cause Kelsey to break up with you if you are with Sola, but you have the option of installing it or not.
I'm not sure how Nalia fits in. I think you could probably romance any of the boys, but not the girls, with her.
And with Imoen, it checks. I think you can still romance Sola, but he's the only one who allows it, I believe.