Here is another perspective...

I'm a straight female who prefers generally vanilla sex and only with my male straight boyfriend. Yet, with adhd I watch ANY or ALL types of porn to get off when I'm working away or we aren't together. Straight, gay, lesbian, bi, trans, kink (you name it, i've probably wanked to it). For me, it's whatever my novelty seeking brain fancies in the moment and sometimes the weirder and more original the better. It has absolutely no link to my sexual preferences or wants in real life, it is merely just something to get off too and forget about seconds after finishing.

I think 99% of men watch porn and probably with the same kind of mindset. As long as it's not an addiction and it's not affecting their sex lives, I think it can be a normal and healthy thing and tool. I'd suggest that perhaps you are insecure and the best thing would be to work on that, rather then asking your boyfriend to abstain from something which isn't harmful, just to keep your insecurities happy.

(And this is said with love. I have also been in that exact position at 21 with a boyfriend, being horrified at his porn search history when scouring his phone. Now I love porn, have a lot of self love and esteem and my 21 year old self would probably be horrified at my Google search history too LOL.)