I was fortunate to find my fiancé. She was already into baseball and Magic the Gathering and when we met, I was into coin collecting. I dropped coin collecting about two years into our relationship and transitioned back to my childhood focus of baseball cards. She has supported my hobby because she has her own hyper-fixations as well.
We also collect Ichiro cards because she is half-Japanese and has a good memory from her childhood where he held her and there are some photos somewhere (I haven't seen them though). Apparently, they have a signed ball from his NPB days over in Kobe, where her grandparents live.
Overall, I think it's more about finding someone understanding about your interests and not dealing with those who insult them. I've dated people before who made fun of mine, and those relationships died quickly.