I [24/f] dislike watching my boyfriend [30/m] play video games, but it's kind of our bonding activity

I'm a hardcore gamer. I've played competitively and even work in the industry. I live with my boyfriend of 1.5 years who is an old school gamer and used to go to arcades and has all the OG gaming stuff (he played original Zelda but nothing after Link to the Past). He had kind of grown out of video games when I met him, but has since rekindled his love for them and is so amazed with how far along they've come.

Here's the problem - he's not very good. He's slow, he gets frustrated easily, he has trouble with mastering some more complicated parts of games, etc. The thing is, he is a genius, but a few years ago after undergoing chemo, he was left with chemo brain. This means he has problems with memory and connecting the dots on seemingly simple tasks. In games, he's slower to figure out puzzles and finding out where to go. For example, we're playing Tomb Raider right now and it took him about 5-6 hours of gameplay to do what I did in about one. I'm not trying to brag about how amazing I am at gaming, but watching him can be excruciating. But he likes when I watch him play. He's expressed frustration before when I showed I was kind of impatient, saying how difficult it was for him to play. But I just can't do it anymore. Am I being a total bitch and should I just suck it up? Video gaming is my life, but watching him play is wearing me down.

tl;dr My boyfriend has some brain problems that make it difficult for him to play video games, watching him is frustrating for me but he likes it. What should I do?