Re: cheater.
^^ he is not cheater, but an opportunist! and its worst than cheater i guess. he may take any better opportunity in the future too, what if that girl become available again?
not all cheaters will stay cheater, as most of the cheaters are in relationship not for real and that thing keep them stay as cheater as they are not sincere with anyone.
i guess if even a player/cheater person becomes sincere to anyone in life for real, then will not cheat.
so key is sincerity for real.