When relationships start to go sour or I sense the other sides interests has dropped then I actively start to consider my options and make new female friends sometimes I’ve already had sex with them before the current relationship ends . Psychologically it’s the best thing to do and when you know a relationship is going to end as it prepares you in advance and you can just move on. Besides, once a girl starts acting different high chance she’s already fucking someone else and lining up your replacement so might as well do the same. But beyond that, when I’m happy and sense the other half is fully committed I’d never cheat and have even turned down opportunities.