Mostly, with relationships, I worry, while in them, about giving up too soon, and regretting moving too fast. Looking backwards, I think I regret not giving up sooner. I don't want to "regret" giving up, but this avoidance of regret leads to regret anyway.
Still, I probably ought to have learned much better about when I am actually just cutting my losses.
Regret. Gets you both ways, doesn't it?