This isn't about seriously abusive relationships, but those relationships you have (often) when young and look back and think 'wtf'.
Bumped into ex yesterday, he wasn't bad, just feckless, younger than me and I was a bit vulnerable and didn't really know anyone in new area. I put up with all sort of crap with him, sleeping around, booty calls, emotional stress etc etc.
I invested so much into that. I'd have been on mumsnet stressing about it if mumsnet had been there.
He moved away, I'm now married to entirely non-feckless man, happy.
When bumped into him I just thought, why did I waste all that emotion on you? If you move on from the daft relationships, that's ok.