Responses
He is not a cheater. The other guy is a sex friend and he sleeps with others too so you are clearly wrong!!!
First: The other guy treats him as a lover at least to some point. Thought we don't know how serious he is.
Second: How the hell do you know if he sleeps with other people if the manga doesn’t shows it. Are you psychic? If you want to use an argument first verify if it is valid.
Third: Get down of your almighty heels, dear. We are all just having fun here.
This is the first time I don't get pissed with a cheater and I don't even know why. Maybe Kanzaki is so messed up that it gets funny and I don't care anymore. (ノ≧∇≦)ノ