I am trying to do the Jahiera romance, and I heard something about the harper quest messing it up sometimes. If I take the quest from Xzar will the Jahiera romance end? Or is there anything I need to watch out for if I do the quest to not make her mad?

If you dont take the xzar quest the jaheria romance never really starts.

There are also a few other harper quests that come up during the romance. go to http://members.rogers.com/mrkevvy/ and find the fixpack which fixes most of the bugs in the romance.

<font color="gold">The Xzar/Montaron-quest is essential for the romancing, meening that you have to do it. ;) </font>