The question as to why people cheat has been like building a ship in a bottle. It’s been asked but rarely answered. But if we can’t answer why people cheat perhaps I can help you know instances he/she can cheat on you.
1. When he/she does not trust you; she has seen dirty flirty texts on your phone between you and other chics. This breach of trust spontaneously makes her think about revenge, and if there’s a Team Mafisi member hitting on her at that particular time then damn man, she may probably go.