Relationships are a two way deal. It sounds like it has been going for a while, at least several months. She has every right to put herself first if she's been in an unhappy situation for a long time.

I went through a down period a few years back, lost my gf of 5 years to it. Her leaving removed my saftey crutch and forced me to get my own shit together. Sounds like it's what the OP might need too.

Man, they didn't have sex for months. The problem comes from the OP, he needs to build his emotional maturity.

That's unreasonable. They haven't had sex in months. Anyway, OP should chalk this up as a learning experience and move on. Develop a more balanced lifestyle.