It can certainly be relieving for one to disconnect temporarily or permanently from sources of upset, if she/he is vulnerable to them. It’s even better, is he/she doesn’t have to do that.
Aside from that, it is also one’s right to only be in contact with that she/he wishes to.
However, the notion that one’s well being is irrelevant to another’s, is utterly false. The ‘I’m going to be well, even if they aren’t’ is a defensive ditch, not free well being. And one needs to hide in that ditch to feel relatively well.
One feels best as all is well. And nobody feels better by harming another, unless he goes even below that, to a point where he thinks he can’t even do that (that’s how you provoke somebody –you imply he cannot do it). Then, the being able to harm brings about a temporary relief too, which eventually burns out and is then followed by worse emotions. One might then seek to harm some more, to feel ‘high’ again; until he can’t even do that, which can come about -sooner or later- in the form of bad health, opposition from others, or other things.
Ethical or legal rules that forbid harming, can bring about what is mentioned above. As one who thinks he cannot harm, doesn’t feel love instead, but uses more sneaky, less obvious ways to harm others as well as oneself. Love is self determined, and self determination is love, and them cannot be forced.