[O__________O]

Just to be clear, I agree it would be harder to cheat for a potential long term mate from an existing social group. That said, if a potential partner was a cheater, it’s highly likely that it would be much easier to figure out if a stranger is cheating than someone from an existing social group, since they already are aware that they need to be careful if they don’t want to be caught.

Said another way, it’s ultimately impossible to know for sure if someone is cheating without reaching the point of being equally toxic by not respecting an individual’s right to privacy, independence, etc.