I've always been curious.
A friend of mine would never cheat but she's gotten involved with a guy who, in the conversations she's recounted, is likely a cheater. For one he can't keep to what he says always changing his words & twisting things around in his favour. Thing is, is she's got a near-photographic memory & can remember a lot of what he says no matter how minor.
Anyway he once said that if you 'cheat on me with someone else that's on you'. This seemed a little extreme when she constantly informed him not interested in other men & had done absolutely nothing to imply she was a cheater while he talks of other women constantly.