"But what if he still wanted those same attributes and found someone with stronger attributes than yours, more money, better carreer, higher class than you."
Chances are they wouldn't want him!
When people cheat, the affair partner isn't special, they are just available.
You're still talking about people as marketable commodities, OP. What about (for want of a better word) their soul? That part of them that aches to learn and grow and live life to the full?
For example, what if they took on too much responsibility too young and long for the teenage fun they never had?
Or, conversely, what if they have always been rather spoilt and indulged, and some vague part of them needs to learn to look after someone helpless, just to prove they are an adult?
These are just examples of the unconscious desires that can make someone attractive to us at various stages in life.
You sound very raw and angry and bitter, which is obviously understandable, but I hope you will at least take a look at this book sample as I think the book, and doing the exercises at the end, might help you come to terms with your painful situation. X