I'm not sure if this exists, or if this is even something that's possible, but is there a mod that stops sims from being shocked by seeing their spouses naked, while leaving the shocked reaction when they see strangers/random sims naked? I know there are a couple mods that remove the reaction in general, but I was wondering if anything more specific exists.

Well, you can start with simler90's Reaction Naked Underwear Mod; however, it'll also make Sims react to other Sims who are in their underwear (the criteria for both reactions are listed on the page, though).

This looks perfect, thank you! I think the underwear reaction makes it more realistic, too.

I knew there was another mod out there for this problem but I couldn't put my finger on it. Now I found it: Cyjon's Less Naked Freakouts

Thanks Corax, this is good too!