Is it the person cheating, or the person being cheated with? Let's assume that the person who is being cheated with doesn't know that the other person is cheating on their significant other.
Most Helpful Guy
I would definitely say the cheater in most if not all cases but I do consider exceptions. I think if a person is abused terribly by their partner and the partner either is forced to stay with them out of fear (e. g blackmail) or the other person does not accept a break up then it is the other persons fault.
I have been cheated on during the first few weeks of a relationship before and only found out a few months after. At the time I was away when we had just started dating and we were both obsessed with eachother (I thought, but still so believe) She felt really bad and was scared to tell me because she didn't want to lose me. I was calm and asked her one day why after being so happy and loving she felt really sad, she told me everything and was begging for forgiveness. I asked her why. She had recently left an abusive relationship and whilst I was away her ex had been over and traumatised her again. She doesn't have many friends so she turned to one guy for comfort, she was drink, upset and missing me (he kinda took advantage) it was early on and nothing else had happened since so I wanted to give it another go and we did. It was only until a few months later in an argument where she blamed my friend for it happening and was glad it happened as we wouldn't have been together today if it had happened. Because I was away visiting family when she called me a lot, upset after the event with her ex, one of my friends was drunk and confused as to why I was in the phone. They simply asked in a sharp way why I was calling so much and to get off the phone. This upset her apparently and made her feel unwanted and a burden to me so instead she found comfort from someone else. I do not accept this and think you either know you're not going to cheat or you could or would cheat. I accepted the apology when she claimed responsibility, but when she tried to shift the blame and therefore remove her guilt, I knew she wasn't sorry and this was too far for me. That was the end of us and yes the cheater was to blame!1
Most Helpful Girl
The person cheating is in the wrong, no one put a gun to their head.2