Hey,
lol i am in my 20's, 3 years married and have never cheated. Never will. I agree with others that honesty or lack there of is an individual problem no matter where you fall on the spectrum. Interesting question though, i knew some people cis couples who had wonderful partners but just cheated for the sake of it, after everything boils down it is more often than not related to one of the partners insecurities as Dena has said.
kind regards,
B