Whether you're okay with it or not and he watches it or not etc is up to you both to work out in your personal relationship.
The part I'd find worrying is the lying/hiding it from you. That would be cause for some marriage psych to me might help you work out what to do about the conflict too (partner likes p o r n/you dnt like him watching p o r n- How to work it out so you can both be happy)
Regardless of what they do or don't/what you do or don't.. The important thing in a relationship is communication, feeling you can talk about things, feeling respected/respectful and trust!
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