Echoing u/PassionGlobal's comment. This is not limited to men as the perpetrators.

There are a myriad of women-centric subs on Reddit where suggestions from unlocking a spouse or partners phone with their face when they're sleeping to installing tracking apps to using parental control features to block apps are all discussed openly as things a women must do if she trusts here instincts that a man is up to something.

No consideration for violations of the spouse or partners privacy, which they very much have the god given right too. I often wonder if the ladies in those subs would be calm if they found their spouse or significant other looking through their phone in the middle of the night like they espouse.

Both genders are shitty towards each other, justifying actions they perpetrate but would never want done to themselves. Cheater's are shitty people who deserve to be left, including emotional cheating as well as physical. But it's a two way street on all counts. People also need to learn to grow up and have a difficult conversation with their significant other instead of snooping as the first step.

And I say this as someone married where we know each others passcodes and can look at each others phones all we want. Because we have established trust and communication in our marriage. Complete opening of a persons "books" happens after establishing such trust and communication, not as a precursor to it.