For my birthday, my spouse got me a nicer newer expensive version of a thing I already have. The one I have is older and dented but works just fine. I use it weekly. I never complain about it. I’ve never asked for a newer one. The one I have was given to me by my mother in law, whom I adore. It’s sentimental.
I don’t like new things. When they got me a 3d printer, it was the cheapest one and it was a kit and I had to build myself. I loved it. It’s perfect for me. I regularly buy things used or get things from Buy Nothing groups. I much prefer to repair old things in many ways. My car has over 100k miles. The one before did too. I don’t like new things.
We got into a huge argument because I want to return it. They are so upset with me that they left the house to calm down. Why am I the bad person? Why are they mad at me? I have a very clear tendency for old broken used things. Why am I obligated to like this new thing?
We literally established a rule early in our marriage. 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. Why am I the bad guy for wanting to return the newer version of the thing I already have?
Fundamentally this gift is replacing something that has sentimental value to OP. That’s not usually a desirable gift. If someone got you a gift that replaced your favorite [thing] in a way that replaces it you wouldn’t want it either.
Cheerfully accepting a gift you don’t like is dishonest. Other replies have great honest and tactful ways to accept or reject a gift you don’t like. Op’s approach was hurtful to their partner which isn’t great.
Returning a gift is normal, that’s why stores issue gift receipts. However, it is a situation that requires tact since it’s easy to hurt someone if done poorly.
In the long term, it should be easy for you and your partner to do something special for each other where no one has to fake enjoyment. In OP’s case, effort spent communicating now will bring a lot of enjoyment in the future and save a lot of pain.