I also find it hard to take to suddenly hear a backlog of N months of complaints ("two months ago, you didn't say dinner was good, and THEN you didn't thank me for emptying the dishwasher!!!") I'd rather hear about things relative soon after they happen. "You've been doing it wrong for months" is hard to take, even if I realize that sometimes such things only become clear after the fact.
I'm okay someone saying "I don't know how I feel" or "I need time before I talk about it" (although those things may occasion worry on my part if it goes on very long).
I also find "why did you do X" comes across as "how could you be so stupid as to do X" or "how could you possibly justify X?" I appreciate it when it's clear that the intent is to understand, rather than judge.
If the other party is super upset, I may get overwhelmed by that and lose my normal emotional awareness, but that's very rare.