Nothing wrong with age differences. I have known many happy marriages where there was a big difference in the ages. Congratulations on your successful marriage.
I do want to reiterate that it is not age differences that is a problem when it comes to sex or relationships. Going back to the original theme of this thread, underage dominants (or submissives), the problem lies with the immaturity of most high schoolers. Some are very mature and responsible, but too many are not and are not truly ready to handle a sexual relationship, especially one which puts them on an unequal footing with an adult as a partner. I have dealt with youngsters this age all my life, thousands of them, so I speak from experience.
Keeping this lack of maturity in mind, as a rule, I would strongly discourage relationships between adults over 19 and teenagers under 18. (of course there will always be exceptions)