I am not meaning to say that someone who cheated 10 years ago when they are 21 should still be a social outcast or that I would even think of them as a shitty person.
Yeah, I believe that their circle of friends ostracizing them is fair and legitimate punishment.
The 30% number comes from estimates of men in women in marraiges:men cheating at 20% rate and women cheating at 13%, so actually 33%.