I had this issue for a long time. My self-worth was in the toilet, and I felt really uncomfortable receiving anything from anyone. H interpreted it as me being ungrateful, though I appreciated the gestures.
I think my W has this issue as well. I have never felt she sufferred from a lack of self confidence/worth. Maybe she was just masking a lack of self worth by projecting an image of self confidence.
Anyway, my W has never been able to accept a compliment. Me: "You look fantastic." W: "Yeah, haha, right."
Maybe this is related to the lack of self worth.
Sorry for the hijack Thinker, but thought discussion on that might be helpful.