I'm curious, is your gf the kind of girl who really, really cares
about almost everything?
If yes, then her relationship with her ex makes sense to me, and you really don't have to worry. Why it makes sense was going to involve some stories about how I converted an old gf from liking girls to liking men. She still really cares
about me, even though I broke up with her almost 5 years ago, and she's been living with a really nice guy for three odd years now.
If she is not one of those people that cares
she might just need to be taken in hand:www.takeninhand.com