Having been cheated on twice by my first and second wives I can give a pretty good answer to why they may have cheated . I think it explains a lot of cheaters actually...I wasn’t giving either on of them something they needed in our relationship...whether it was more of my time or displays of affection or any number of things...now they may have said what was lacking but I must not have listened and that is when they went looking for what was lacking ...because generally they cheat because they aren’t strong or brave enough to leave the relationship until they know they have somebody else who says they live them...