Please help me

I never thought I would be posting here to be honest with you. I was just told last night it isn't you it's me and I'm not happy with myself thing. We have been together for 7 years. We were going to get married next year and get a house. I know we do have a codependency and I have a hard time talking. For all 7 years we have been like friends with benefits. We never get into fights. At first I thought aww how cute and now I can see that it's not healthy. I want to fix it and I can't. I sounds so crazy right now I don't know what to do with myself. I'm at work and I can't even work right now. We have broken up almost every year right around this time. Every Nov like clockwork and then in about 5 days she will come back just as sad as she left. I know it's not cheating or wanting to leave me for someone else. She is depressed and won't get help. She will come back and I will take her back, but not this time. I think this is it and it's killing me. I feel like a doormat and want to know why this happens at the same time every year. How do I convince her to go get help? She was molested as a child and has never talk to a doctor about it. She has social problems and has a hard time understanding when people want to be friends vs. hitting on her. Is there some resource I can find to get her to talk to a doctor? We have health insurance so that is not a problem. I don't know where to start. I know I am going to get a lot of grief for this, but I just want to fix her head. Everything else is so great about our life together. We love each other so much. I know I should just hit the gym. It's not that easy. If it matters I am a woman as well. TL:DR Girlfriend is depressed and sad won't get help. Says she wants to leave. Can't let her go. Says she still loves me but can't keep hurting me anymore. Kissed me goodbye right before I left today. Cuddled me and held me while I cried. I can't let this love go. Edit sorry about spelling/grammar I am not in my right mind right now.