It's funny you consider adultery to be a sign of immaturity.
As far as I know, just by nature of there being more short than long relationships, In most cases cheating occurs rather early; so its a massive waste of time for every party. Seems short sighted and immature to me.
Not telling you you're wrong, just asking for a different take.
https://www.psychologytoday.com/ca/blog/the-myths-of-sex/202...
https://www.businessinsider.com/how-long-married-people-wait...