This is sad, and it doesn't reflect especially well on either party. Here's the thing, though: we evolved in a world where being expelled from the tribe was a death sentence. When people fall out, often their instinct is to try to preemptively convince everyone else that the other guy is the evil guy who should be kicked out. To convince everyone else to take a side.

We don't live in that world any more. You're not gonna die if you don't convince everyone that the other guy is the evil one. It's perfectly fine to decide that you just can't deal with someone else, and you can do that while accepting that you don't need everyone else to take a side or be convinced of your reasons.