I don't mean cheating, committing a crime or anything immoral that would obviously end the majority of relationships. I mean the one singular hill you're willing to die on that others might not agree upon but you will not budge.
Mine is STI screening. I need everyone i sleep with to show me a RECENT full screen negative (not tell me, show me) before I even consider letting them touch me. I've been told its unnecessary and overkill but I will not budge. Refusal to do a test or show me the result, instant block.