I think in the context of a loving dynamic you wouldn’t mind this at all
When I read this I assumed you were referring to a family member using a mug you preferred, which made sense - then realised you meant about OP’s reaction to her dad’s possessive/ obsessiveness over his mug.
These are scenarios that make me think I am possibly ND bc there are countless examples of stuff that matter to me that loads of ppl say is totally ridiculous - why would anyone care, etc. Then there’s stuff like this, where loads of ppl are saying that they too have their own favourite mugs that nobody dares use out of respect(?), and it seems to be a commonly-accepted, ‘normal’ thing to do. Really?! Why? It’s a fucking mug. Why can’t anyone else use it?
To ppl this applies to - Do you mean ever? Do you mean at the same time someone is making a brew for everyone and they take it rather than you? Weird, as you have can have it the rest of the time but I guess understandable. Can they touch your mug? What if you don’t want to partake? Why can’t they use it if you don’t want to at that particular time? If it’s washed up, primed and ready for your use in between, what fucking difference does it make? Are you scared of germs?? That it will be contaminated? And yet you’d probably happily use a public toilet seat and eat with publicly-used cutlery and that’s not a problem.
And this deep-seated emotional attachment seems to be a widely-accepted thing. OK..
Same pertains to seating, which a PP mentioned - sorry to derail, but why can nobody else sit there? Because you’ve decided you like that chair or spot no one else (including ppl living with you) is ever allowed to use it? Ever?
My parents and FIL do this - it’s never communicated verbally but it is clearly THEIR chair and I freely admit to being an arsehole and sitting there every so often to see how they react. They get full use of it when ppl aren’t visiting so why the bloody anxiety/rage if someone does sit there for a short amount of time is beyond me. It’s territorial and often hierarchical. If they were to say please don’t sit there, I prefer to (for whatever reason) it’d be different, but this non-verbal expectation that you just know it’s ’theirs’ or the sense they are pissed off you are sitting there, without having asked you not to - just fucking sit in another chair/room or make it clear if you don’t want guests sitting in your bloody chair! Would it kill you to sit in another for half a hour or more? Would the mere sight of someone other than yourself sitting in your favourite chair occupy your thoughts so much that you’d be unable to participate in conversation and be silently seething at the very image of somebody else just sat there enjoying the physical paradise that is your chair? Are the chairs programmed to spontaneously combust if the wrong person is sitting in them?
A simple ‘I’m sorry to be one of those, but would you mind if I sat there please, it’s better for my back’ would be more than suffice and avoid the whole expectation of clairvoyance.
Better yet, piss all over it to make it abundantly clear it’s yours. Other ppl then wouldn’t be tempted to sit in it in the first place and you’d have the immense satisfaction of marking your territory and no words need be spoken at all.
*same advice follows mug use.