I think it depends on what kind of experience you have, how far things have gone, what kind of person you have on your hands, etc. Everyone is not the same of course. But if you’re dealing with someone who maybe has a personality disorder underneath it all (or whatever they are on is making them behave in a similar way), the very act of being kind or supportive might trigger the person, and trigger their inner turmoil/ push-pull dynamics. It doesn’t make sense, but if there is core trauma, coupled with alcoholism & drug use, a lot isn’t going to make sense. I think people do the best they could for the most part, given what they know at the time, and despite best efforts, being on the receiving end of that non sensical behavior gets to be too much, and parting on good terms isn’t always possible.
Add to it you might have the type of person whose substance abuse makes them a bit predatory, and they might sniff out kindness and use it to their advantage (keeping the person around in case they need them in the future, or to get money out of them, or a place to stay, etc). The person on the receiving end might have years go by and eventually get sick of it, and things don’t always end on the best of terms in those cases either. I dont know, this is hard stuff. When I hear about a person finally getting pi**ed off enough to cut off contact after years of trying to make it work, I’m usually routing for them on the inside, that their anger will be used as fuel to get them through it. Oftentimes the opposite happens, and the sympathies and wanting to be nice no matter what end up keeping a person stuck, or putting them in harm’s way.. It’s a sad reality, but that does happen.