Not at all surprised she left, I'm more surprised she lasted this long. How long do you expect someone to keep working for a company suing their spouse? It's just part of the animosity between Punk and the WWE, so it shouldn't be surprising that AJ Lee would eventually remove herself once lawsuits started flying.
I'd expect a Diva's shelf life to be pretty limited anyhow. She had her run, much longer than it needed to be. Typically, the WWE picks a charismatic character, puts her to the forefront for a year, then they just fade well into the background. So it makes sense to leave while you're still getting promotion on TV as it can all go away very quickly.
She was right to milk it while she could and to leave once it longer seemed worth the work and time away from her husband.