I can relate!
I'd wear the same thing day after day if I could get away with it, but basic hygiene lessons got me off that as a preteen.
Nonetheless, throughout highschool I wore what's called vintage now, but basically I'd just grabbed all of the things my mother had put in the 'donate' box after she cleaned her closet one time... all the clothes she'd worn 20+ years before. Then gained weight as an exchange student and couldn't fit them anymore. That started the black clothing phase that carried me through college. I wasn't depressed or goth, it just seemed simpler for laundry, etc.
Some time back I went to Goodwill with a friend and noticed that everything there was newer/nicer than everything I was wearing, both at home and to work. WAKE UP CALL! Turned out she'd brought me there to 'show' me, since telling me on occasion hadn't registered.
I somehow grasped the idea of costume instead of fashion and that hook seemed to register. There's a work costume, a going out in public costume, special occasion costume, etc. That made sense.
My work costume consists of black skirt or trousers, always, and some blouse/sweater and jacket that I made a point to buy in colors after the same friend told me she'd throttle me if I bought one more article of black clothing. I started with neutrals, beige, grey, etc., and then got courageous and added some colors according to the season.
At home, though... well.... From the time I got home last Friday until Monday morning before work I wore the same black t-shirt and black yoga pants.
The idea of wearing costumes somehow makes dressing 'appropriately' more acceptable. But sometimes I still don't quite get it. Some time back a boyfriend said he had a longtime fantasy of a girlfriend one day meeting him at the airport in a bunny costume. I thought, hey, I can do that. Next business trip I met him in a bunny costume. The Easter bunny. While I was photographed by tons of Japanese tourists (this was in Seattle), and he laughed hysterically, mostly with embarrassment, I was genuinely shocked when he said he'd meant 'like a Playboy bunny". Oh well.
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When two elephants fight, the grass and trees suffer. -- King Sunny Ade