Well, Jaheira is probably just a blue eyed blonde and that's why she didn't warn "us". She didn't know that there was anything to warn from. Despite the fact that she didn't personally like that dude, she's pretty "lawful", meaning that she doesn't break the rules unless these are wrong, in her opinion.
As for romances, then I went with Jaheira last time. Wanted to take it all the way to end, and since I knew that it was long, I was deliberately wasting my time on any occasion. And so it came to pass that the romance was finally finished in Chapter 2
Boy what a long chapter that was, longest I ever had.
Right now I am playing with my paladin, taking him through BG1 and then to BG2. Maybe I will this time try to go with Viconia, i.e. turn her to the good way and all such mushy stuff, what we do-gooders paladins do
Now I know also why I aint such a big fan of paladins and rangers and such - my fighter is so much better fighter. Really disheartening to see someone stand in FRONT of you, then you swing at it 4 times with BIG 2H sword and miss. Bleh...