I was more affected by my mother's words than by the event itself. The reason is that I felt deeply betrayed by my mother (which happened so often that I find it odd that it still affected me).
Pencil, from what you say here it sounds like perhaps you had emotional abuse in your childhood, and it was not one act of betrayal by your mother at that age that affected you so deeply, but the betrayal as a continuum of past trauma? If that was the case you would not have been affected by that single incident of betrayal in isolation, but could be looking at childhood trauma.
Perhaps for people who have been cheated on and consider it traumatic, that has happened against a background of some level of abuse in the relationship, and therefore it isn't the act of cheating on its own that is affecting them, although that's how they're seeing it. Some people can't even recognise relationship abuse, but are forced to recognise cheating so that's what they're focussing on. I'm not saying that's true of people in this thread, it's a general point.
shoulderblades, is that what you're referring to? I'm afraid I'm not sure I understand what you're saying. If I've understood correctly, I still don't think it affects the issues of whether cheating can be compared to rape. If you're saying cheating following past abuse or following a history of abuse from other people (of a type which would be classified as trauma) can be compared, then firstly you're talking about trauma and not cheating in isolation. Secondly, I still think comparison of different things is meaningless.
I feel like the topic has come full circle. I feel like we're right back to needing to look at the DSM definition of trauma, and that cheating and other betrayals, however devastating in their own right, are not a trauma in the sense of possibly causing PTSD. I feel like the issue has been confused with other things which are traumas, and it needs to be separated out again. I'm not even sure what reductionism is, probably what I'm suggesting, but if you don't draw a line then how can you ever make a diagnosis?
For me, saying that it's connected to other things doesn't mean the question is less clear, it makes it clearer. If it's connected to trauma, then that could make it an overall traumatic experience. In itself, it's not a trauma. I see no validity in comparing it to a different type of experience, especially not as a way to classify it as a trauma - which I feel is what Core was describing about the other discussion. (I want to repeat - I'm not saying being cheated on is not devastating, I'm talking about the definition of trauma, and making comparisons.)