This is a simple guide to her:
Try to do choices that would generate approval from her. If you must do something that is against her desires, then at leave remove her from group.
Have her in group as often as possible as many choices you make she will approve or disapprove.
She doesn't sleep with you untill least the start of act 2!, you can't get her to admit love untill you finish her quest in ACT 3. There is no way around this.