I know (or maybe just vividly imagine ) what you mean. This is probably just me, but I hate making decisions based on "someone told me it was a good idea". To me, an informed choice includes having a sense of what's likely to happen if I do A, what's likely to happen if I do B, how I typically react when either one happens... and how willing I am to invite it to happen and see if I can find other ways to respond.

For me, a good reason for staying away from someone would be: I can count on them to do stuff I find it hard to deal with; I've considered working through my reaction to whatever it is they do, seeing what's on the other side of it, and learning from the experience whatever I learn; even though I see benefits to doing that, it still doesn't seem worth the trouble.

A not quite so good reason, to me at least, would be: I hate it when they do whatever they do; they're not willing to stop and I can't make them; I don't want to put up with it; so for my own protection I'm outta there.

I don't like giving up on somebody. When it looks like it's not going to work out and I've invested as much as I'm willing to, it's actually kind of convenient when they decide to leave first.