I cope with my girlfriend looking at nudes by giving her space to do so in private. By giving her the room and the freedom to have whatever sexual fantasies she wants.
By supporting her whenever she wants to go out for a night out without me. And sending her off with a "Have a great time."
Whenever she asks me if she can go off and do something without me - eg a long week-end in Barcelona with her mates - I've always said "Of course! Please go ahead."
When she went to watch some male strippers, it was fine by me.
I cope by regarding it as nothing to cope with. Really, absolutely nothing to cope with.
I know that I am not the most physically attractive man in the world. And that there are a lot of women that would turn their noses up at me, simply because of the way that I look. But that's fine, because there's an abundance of great women with somewhat of an open mind when it comes to looks.
Cute compliments? I don't give two hoots about them. As long as we are going on adventures or mini adventures, then that's more than enough for me. With mini adventures including our love making sessions.
I think that you would function better if you adopted the same outlook on these things as I have.
It's entirely up to you if you transform your basic life philosophy on this.
At first it might seem like swimming without water wings when you let go of focusing on what your boyfriend(s) do when they are not with you. But you will find that you don't sink and you swim better when you let go of this baggage.
Although having said that, if I were with someone that was spending like 14 hours per week looking at pornography, I'd probably dump them and look for someone with a less addictive and less time wasting personality.
I've found it's generally pointless begging someone to change an ingrained habit. You can lead a horse to water, but you can't make him drink.