If talking about something is upsetting for you (not triggering, but definitely annoying and frustrating), is it okay to ask someone not to talk to you about it? Is that setting a boundary or just pushing people around?
In almost all cases, that is setting a boundary. Generally speaking, you don’t have to discuss things with people if you’re not interesting in discussing them.
Some exceptions I can think of:
  • If you’re teaching someone something, and they’re confused and explaining why they’re confused, it’s not usually ok to say that you don’t want to hear about it
  • If someone is explaining why something you’re doing is hurting them, it’s often not ok to say you don’t want to hear it (but sometimes it is. Eg: if someone wants to say you have no right to break up with them because it’s breaking their heart etc)
  • If you’re that person’s therapist and what they’re discussing is within the scope of therapy you have agreed to provide
  • If you are someone’s doctor and you’re finding their way of describing symptoms rambling or otherwise annoying, you almost always have an obligation to listen to them anyway

But you don’t have to discuss things with someone just because they’d like you to discuss them. You don’t have to have some sort of cosmically compelling reason, either - absent a specific obligation to discuss the thing, finding the topic boring or just not wanting to for whatever reason is a perfectly good reason to decide not to.