Hi and welcome to YT
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Well, yorkies can def be extremely quirky, dramatic, and goofy - so I'm not totally surprised at this odd quirk of hers. BUT...bc this is sort of "isolating" type behavior I'm actually worried that something could be wrong your little one. When dogs are in pain somewhere or not feeling quite right, they'll often be lethargic and/or isolate to one area.
I would perhaps palpate her body all over, and I'd also give her mouth a VERY good inspection - looking at and feeling around the teeth, and notice if there is a bad mouth odor too, indicating a dental issue and possible pain.
If this isolating behavior is sort of sudden, then you kind of do have to wonder if something is wrong/bothering her or something. But I just don't know.
Also sounds like she is doing what is called "resource guarding" (google it for more info) with food/trash/bones...and maybe even her bed now. That's something you really want to nip in the bud if able via training...