Cheating on who?
On your husband? Not okay, for a host of reasons that have nothing to do with morality. As someone who dabbled in being The Other Man when he was younger, I don’t recommend it… marriages are complicated, legal constructs that need to be dissolved when they go bad.
On your owner? Probably not okay, depending on whether that label is accurately descriptive or simply a ceremonial title. If someone owns you in a meaningful way, you’ll never forgive yourself, even if it seems as though he objectively deserves it for being a prick.
On your boyfriend? Pfft. Boyfriends exist to be cheated on. That’s why they’re just boyfriends and not something important. You’re not cheating on your training wheels when you take them off your bicycle and ride free.