Second, sometimes when some people face some problems in such love relationships, they may think of going out, or getting into new relations for many reasons.
They may want a break to think differently. If they intended to do this, they will get away of any relation.
They may also do that for revenge, or to forget the first love, or just because of some level of craziness.
As long as she couldn't "give up with her current boyfriend" as you have mentioned, you should know that you haven't made anything to help her overcome that past relationship.
She possibly has involved with you because of one of the reasons I mentioned above. You'll only know that through the way you deal with each other and when you think of what you actually do every time with her.
According to what you have mentioned, she still loves him. So, be very clear about this and go a head to discuss with her and tell her directly to decide.
She will stay with you, if she really loves you. Otherwise, don't waste your time in such unserious love relation. Love always comes with the right person in the right time.