OP - supposing your problem wasn't with watching nude scenes on TV, but about something bland like "I don't like cabbage"?
Your b/f likes cabbage.
You do not like cabbage, & your b/f knows this.
Instead of just cooking cabbage for himself, he puts cabbage on your plate too, & demands that you eat it. He says things like -
you need to stop feeling that you dislike cabbage
all his past girlfriends haven't had a problem with eating cabbage
all his mates talk about eating cabbage
he forced cabbage on you to the point that you started crying & his response was to tell you to snap out if it
He is being so demanding & single-minded about forcing you to eat cabbage that you have ended up feeling dreadful -
I asked if we could skip it if cabbage was on the menu but he doesn't want to do that either.
He makes me feel so bad for this genuine feeling of disliking cabbage
Do I need to see a doctor for a medical treatment that will make me enjoy cabbage?
How can I be the person who likes cabbage?
OP - you NEVER NEED TO EAT CABBAGE AGAIN.
Ignore PP telling you that you ought to.
There are plenty of happy, well-adjusted folk who don't enjoy nudity on TV. Or cabbage! That's just a preference. There is no 'normal' to that preference - each individual gets to choose for themselves.
Please do, however, pay attention to PP urging you to get help with understanding the causes of your body dysmorphia & the insecurity/jealousy that likely stems from the same cause.
You don't need to watch sex scenes - but you do need to be more comfortable with your own body, & find a way to be mroe comfortable with accidentally seeing TV nudity - it's so prolific now that you are bound to see it occasionally, & you deserve help with finding a way to deal with that with far less distress.
So ...
See a GP. Get signposted to counselling or other MH help for the dysmorphia. Explore where it comes from & how it relates to your general insecurity, & learn ways of addressing it.
Also - dump this man. He's happy to make you cry because HE WANTS to make you watch scenes that upset you. Ditch that cabbage-loving bastard!