Obviously the target has agency, I don't deny that, but it seems blindingly shortsighted to think it's as simple as "be suspicious of supermodels who are into you".
I agree with you, but, brain chemistry is weird, and "wouldn't cheat on them" is easier said than done and requires a lot of discipline in the heat of the moment when the situation arises and your own hind-brain and hormones are fighting you. A blasé attitude won't prepare you foe the sucker-punch.
I've seen grown people with multi-decade relationships throw it away because they got a tiny bit of extra-marital romantic attention, and the thrill regressed them to teenagers. In the majority if cases the cheaters' amors weren't interested in a long-term relationships.