You can be her friend, or her lover. Goes for both sexes.
Although to be her lover as a woman, you apparently need to answer her first dialogue exactly right. I've taken three characters through so far, all women, all with perfect affection. So either I missed a later dialogue option or she will fall in love with, but not consummate with elves. :\. Yes you do need to ask her a specific question, when you talk to her about her past she will mention something about being in love with Marjolaine. One response after she makes that comment is something like, "so you enjoy the company of women?" You must pick that response to start a girl girl relation with her