Ask Lemmy

In that case, here's a plausable explanation that might resonate:

Gifts are a social contract. They are tendering their time, effort, and feelings for you to pick something to make you happy. If they misjudge you and you care about their happiness, thank them, hug them, make them feel special, then make sure you have a gift list available to them next time. This could be a Pinterest board, or anything. Focus on things you'd consider acceptable, even though they're new. Also, DON'T GIVE THEM THAT LIST RIGHT NOW. In fact, wait until black Friday and tell them you have trouble picking out gifts for them, and ask if they could make a list, and can then, hopefully, safely exchange lists.

Your spouse put a lot of time and strong feelings into picking you birthday a gift. They formed an emotional attachment to this process/gift expecting to make you happy. Perhaps they feel like they don't get you good gifts, perhaps the price of the item itself was a hardship that they decided to bear on your behalf to make them feel proud, or maybe they feel like you're too good at getting them gifts. Perhaps you're extremely hard to shop for since finding you used, repairable items that you'll appreciate is an insurmountably difficult task from the outside. In any case, they felt that they had done a good job and probably had a solid sigh of relief for figuring something out.

They wrap it, feeling excitement, wanting you to be happy. They hand it over to you. You appear disappointed and want to return it. Even if you put on a good face at the time and later mentioned returning it, All that excitement, pride, and serotonin they had is now instantly gone. They feel awful for not understanding you.

Embarrasment + Shame + Sadness will make some awful anger.

Pick your battles. Someone giving you something nice that you don't love for your own reasons is rarely a battle worth having. Accept it with grace and admiration for them. Make them as happy as they're trying to make you.

edit:

also to cover

I’m not allowed to gift nerdy t shirts. They don’t like them. I love them. I thought they would like them but they do not. So they asked me to stop. This feels the same. I do not like new things

While not entirely incorrect here, they are adjacent, but gifting clothes is another type of social contract with some messy implied stipulations. You give it to them, they feel obligated to wear the clothes and that usually comes with public-facing consequences. Self-image is quite fragile in the face of others.

I keep a collection of nerdy t-shirt logos from t-shirt sites all over the net in an image account and my wife has access to it. She can get me anything from there in my size in any form of clothing and I'd gladly accept it and be overjoyed and wear it all without worry.