First off, I'm sorry you're in this stressful situation. Though I'm happy that your girlfriend has been so supportive of you while you transition, I don't think that it's fair to use your transition, something you did not choose- yes, you chose to transition, but not to be transgender- against you. You can't compromise your morals and you shouldn't have to. If she had say, cheated on you, would that be okay because she helped you transition? Of course not! That's not to say, you should kick her out immediately upon her return home. She obviously needs help. You said this isn't the first time she's committed theft. I don't know if she's doing it because she's in desperate need of something or for just the thrill- neither is right, but at least if it were something she felt was a last resort- say stealing food because she was hungry, the circumstances would be a little different and would be looked upon more leniently. That doesn't sound like this is the case, though, as she obviously has you in her life as a support system, just as you have had her. I think you might need to sit her down and see if she'll seek treatment for her problem. Perhaps it's an addiction or compulsion. If she's unwilling to seek treatment or help and refuses to stop her behavior, then I think you have to ask yourself if that's the kind of person you want to be with. I don't know if you're living together, but what happens if she commits theft one day and harbors the items in your home? You could be found culpable, as well. It's obvious you care about her and I urge you to get her the help she needs-she has to want it, though-, but you're not a doormat because she helped you transition. You deserve someone who respects your morals and ultimately respects you.