Hi lovely, sending you a big hug, I have been through this myself and its utterly miserable and feels quite isolating because it's not common to feel that way so you feel like there's something wrong with you "why can't you feel normal"
For me it was a combination of feeling angry that to/movies are still very much all for the male gaze, nudity is mostly sexy if it's female but funny if it's male. Feeling insecure in myself my body and jealousy of my partner seeing other women with stunning/perfect bodies on tv.
What I have recognised now that I'm no longer like that is that it's not really about any of the above, it's about anxiety and insecurity and that just happened to manifest in the above until it got completely out of hand, I didn't even like my partner watching those things even when I wasn't with him (talk about bat shit) he's a huge GOT fan, I'd get jealous of him even talking about it, and it wasn't like he was raving about the sex scenes.
Now he can watch all that kind of thing and I don't bat an eyelid. I still don't watch it with him but that's because GOT ain't my thing, however these days I'm quite happy for it to be on whilst I do other things if he's watching it, I could never have coped with that previously.
I tried completely avoiding all things with sex/nudity (hard to do, it's in most things) I tried forcing myself to watch things containing it with him. But neither of those things really helped. What really helped me was actually getting therapy for the underlying causes because like I said it's never really about those things that's just how it manifests its self. I thought I'd always be like that because this isn't something new for me or something that's only happened in my current relationship. Please seek help through therapy they are there to help you not judge you, this is something that you can work through and get over I promise.
Dont let anyone shame or belittle you for feeling this way just because they don't feel that way and they don't understand why you feel that way doesn't make your feelings any less valid. I'm not frightened of spiders but it doesn't mean I judge or shame someone who is, we are all different.
you can get help with this and get through it x