Cheating.

Cheating is only cheating when you're keeping secrets and telling lies. Also, it's not cheating if there is no commitment. So in order to avoid messy misunderstanding, a man may insist that you and him remain friends. He is single and will shout it from the rooftop. He will not acknowledge you in public. This is all to remind you and he are not exclusive. He can sleep with whomever he choose.