Heartbroken. Help girls. Is this familiar? What's she feeling?

here's the deal.my gf of a year had been bickering for 3 months.i wasn't unhappy until she started having 2nd thoughts about everything. i could tell it was going downhill as she'd be very inconsistent in the way she acted with me.we'd go out to a bar w/friends, start arguing, i'd leave, she'd call or txt me telling me how sorry and messed up she was but that no matter what she loved me more than she'd ever loved another.i know she meant it.well, i told her too many times that i'd do whatever to make it work, giving her too much leverage. she never felt threatened.i finally had been in limbo enough and forced her into breaking up with me one night.this was 2 months ago. we went a week w/o contact.i then called her to have lunch and end it right.she then started telling me how much she missed me. we went out one night, had a great time, she spent the next 3 nights over and things were great.well, then she hits bottom again w/o warning.this went on for another month.on and off again.