I'm going to leave my struggling girlfriend.
Why do you want to leave her?
She needs to move on from the past or we won't be able to move forward in our relationship.
If your girlfriend is struggling you shouldn't be making things harder for her by leaving. I suggest you to stay and help her through her troubles.
Why should I stay and not do what I want to do?
You should want to stay with your significant other and support them as best as you can. Communication is key in any relationship especially if you want it to move forward.