Thank you - this comment is really helpful in getting me to tease out exactly what's happening. One thing that I've realised on reflection which seems quite significant is that the only emotion it seems to happen with is sadness. I don't have any difficulty identifying when I'm happy, or angry, or scared, or guilty, or embarrassed.

I think that probably means that it isn't alexithymia, and it probably isn't straightforwardly about conflict avoidance (although I suspect it does interact with the latter unhelpfully).

The thing about putting it off until later because "processing emotions takes spoons" feels like it might well be a big factor. I think another thing might be that it's quite hard to distinguish sadness in particular as a seperate thing from depression, and although I haven't been depressed for a very long time now, because I was for so much of my formative years, I didn't learn "this is what sadness feels like" when I was doing that with all the other emotions, and somehow it's never managed to catch up.