I don't know Arathor, Viccy is one bizarre chick even for a Drow. I've done this romance many times so I may be some help.
Unlike the other romances you may have played, you can and can't act the same way to Viconia like you would've the others. Saying nice things to her will get her to stay, but she also doesn't want you to do it all the time, she see's it as a sign of weakness. Stand up a couple of times, and she'll see it as bravery or something to that effect. Just
do not make her mad or you'll be royally chewed out
If it's a bug, try un-installing and -reinstalling the game.