What's our (couple) thing???

My boyfriend likes Anime. I used to like it in middle school, but became uninterested when I started high school. We're both nerds, but he's more nerdier than me. We've been dating for almost 4 months now, & he wants me to get into Anime, so that could be our thing. like, even going to the nerd conventions & dressing up. I don't have a problem trying to get back into Anime, but for these past few weeks, I can sense that he's getting frustrated with me forgetting things that are a big deal in Anime related things that he shows me. The first time we had this conversation, it led to a bad-ish argument.

Tonight, I'm not even sad or mad about it, but disappointed? I mean, he. was a bit pissed about me forgetting things again. especially since I kinda fell asleep too. How do we find our thing as a couple because although I don't have a problem trying to get back into anime, I'm pretty sure there's many other couple things that can be our thing. I just think he wants anime to be our only thing, when our thing can possibly be many things. We just haven't found our own thing yet. I don't know what to do, but I really would like some kind of advice because if we have to have one more conversation like tonight's, I'm probably gonna get annoyed.

I was afraid of even having to have a conversation like this again after the first time this happened. Someone please give me some advice. I'm begging you. Thanks in advance. I'm 21, he's 19. We were friends before we dated, & in a few days, it'll be our 4 month anniversary of us dating.