Lisa, my mother is similar. I buy all her clothes, but she really only wears the super duper practical Land's End ones that I buy on sale. Once or twice I got her out to a shop and she bought some truly "nice things" by her standards -- a Louben jacket, two flattering skirts, some pretty blouses. Some lovely costume jewellery. And -- guess what? She never, ever wears them!! In fact, she has forgotten that she has them. She also forgets the nice quality crepe pants and blouse I got her a few years ago for Christmas. (She doesn't have dementia, by the way...at least not in any serious way. But she's legally blind, rarely goes out, etc. And she "saves" nice clothes for special occasions. Which means hardly ever wearing the things she has.)
It's a hard legacy to live down. I have tended to follow her example (until YLF) -- not buying much of anything for myself. Or (more accurate) I took a sort of famine or feast approach; either starving myself of any new (let alone nice) things or buying up more than I could really afford in a quick rush. Part of this had to do with constantly fluctuating, insecure income. And yet part of it was about that feeling that I didn't deserve anything.
The funny thing about my mother is that I can tell that as a young woman, she did have a few nice things. Not many, but some, and she wore them with pleasure. She still talks about a Harris Tweed suit she got when she was a young woman working in Montreal.
I like what Aziriphale said. We should all treat ourselves from time to time and enjoy our beautiful clothes.
Angie's first rule is: Have fun with fashion.
Her second rule is: WEAR THE HECK out of your beautiful clothes.