The problem is that I am going down the good path. Since Viconia is Neutral Evil, she hates the fact that she has a reputation of 20! It isn't because I've been mean to her, she wants to leave because she's the only evil character in my party! When she wants to leave she says "the next time we meet, it will be in battle!". There is no dialogue option for me to beg her to stay (perhaps you are referring to a later romance dialogue).
I have ToB installed so I know that the romance will continue (if I play my cards right). Is there any way to keep her happy AND continue down the good path? Please help, because I need some Drow lovin'.