Temper And Constant Annoyances

My girlfriend and I have been dating for 3 months. We've been really close for years before though so I pretty much know everything about her.

Recently she been getting annoyed at everything I do. I don't do anything to warrant it. She just flies off the handle. We were pretty serious in the beginning but she's dropped us to casual status.

She's only happy anymore when she drinks. She keeps saying we're not married and I'm too close to her. She's been depressed lately and anything I do to try and cheer her up pisses her off. She sleeps all day. She doesn't want to ever just hang out.

I want to know if it will ever get better or if it's too unhealthy to stay in it.