Why would he cheat?

So my man and i have an open relationship... or did. The only rules he had to follow were 1) tell me when he was talking to a woman about sex 2) not do it in our bed or fall asleep in bed with the woman and 3) tell me before anything happens or if it was a drunken night right after it happens. Now really is that asking to much? I mean on mothers day he had sex with his bestfriends mom and didnt tell me anything. I had to pry it out of him and got told 2 days later. Now i consider that cheating but he doesnt because its ok for him to sleep with other women. What do you think?

I think you're trolling.