One can always find exceptions. There are people who will never cheat, perhaps even it they should by most humane standards. My point is there are things one can do to reduce the probability of a partner cheating. Communication, proximity and paying attention are help keep a partner from straying. Even a vegetarian can be induced to eat meat if they are starving. Humans are animals whose behaviour is influenced by its surroundings.
Second thoughts can generally be amended with judicious action; injudicious actions can seldom be recovered with second thoughts.
--Cyteen by C.J.Cherryh