Get help from a professional counselor. If you can't find agreement on sex, you can't survive as a couple.
Find one who does.
Huge boo boo that you went back,,,, wtf were u thinking dude,,lol. What's d point of having a g/f b/f if there's no sex ? May as well hang out w/ur bros andsis,, lol
You have nothing to do with it. It's not your fault. I think she was molested or harmed sexually in some way in her past. Because of this, she's terrified of being touched or having sex with someone.
The reason it just stopped is because something scary happened for her. I believe it's because memories of past pain rose to the surface. She NEEDS to spend some time with a good, qualified therapist to sort through and come to terms with the hurts she's feeling. Until this happens, she's going to be afraid of being affectionate and sexual with you. It's just too painful for her. Her seeing a therapist will help her and help your relationship.
Leave now. She is beyond repair and it will only get worse. Leave and don't look back. You've wasted 2 years; don't waste more.
She went bonkers. Move on.