maybe he is really good friends with her and cares for her.
Probably that he wants to sleep with you and keep his other relationship intact. He wants his cake and eat it too. If this were not so, he would have broken up with her already.
You be loyal to the bf you already have,
This may not be the answer you are looking for, but you can't make her like you. If she wants to like you she will. If she is happy in this relationship, don't take her out of it...
If you are are talking about a romantic relationship, the answer is no. By definition, a straight girl does not want a romantic relationship with another girl.
Most likely he is feeling guilty for something he has already done.
This largely depends on the relationship you have already established with the girl and the question she asked. It could be a variety of answers, including she likes you and wants to be in a relationship with you, or you are a trusted friend and she needs relationship advice.
Usually it is a person who already has college credits and wants to transfer them to another school.
He shouldn't, but he CAN do whatever he wants.
He wants to see your reaction. Plus He wants to see how much the relationship really means to you.
You know if he wants a relationship with you if he says "I want a relationship with you"
Because she wants to know more about you and your family. Probably because she wants to have a serious relationship if you're not already in one with her.
Realize that he was just using you for sex and move on.