I haven't been in any abusive or even just bad relationships. They've mostly been pretty nice. But when I look back from my fifties on previous decades, the big achievements, big adventures, things that I look back on as "a life well lived" have almost all been while I was single.
Because for me personally it's very hard to step outside of the female socialisation of "putting the relationship first" and the men I've had relationships with, though nice blokes, haven't stepped outside the male socialisation of putting themselves first. Net result - their behaviour ends up being a bit selfish and I'm way too accommodating of that.
Not abuse, simply sex stereotypes in action. Maybe I should have been a bit tougher, but if you're having to consciously think about "being a bit tougher" in a relationship, then it isn't working.
I'd have loved a true relationship of equals, and had one ever been on offer, I think I would have ended up happily married. But I never stumbled across one, and find I'm happier on my own than in a second rate relationship. (Not abusive, just second rate. Why settle for second rate when you only get one shot at life?)