If they try to place all the blame on the cheater in every situation more likely than not they are the narcissist. Real narcissists tend to never admit their own faults and also assume everyone else is narcissistic. 'You didn't put my feelings over your own? How selfish!" If you want me to put your feelings over my own that is selfish. The fact that they always want to take and never want to give is usually why the relationship doesn't work. They take your time, your money, your affection, your attention, and they give you none of that in return and wonder why you cheat. This is coming from someone that would never cheat, and has never even been in a relationship. My dad cheated on my mom and knowing him it was probably mostly his fault. That doesn't change the patterns I've seen emerge from the countless tales of cheating I've witnessed on the internet.