Is ADHD underdiagnosed?

I'm reflecting on the amount of real life current stories I hear about marriages turning out more or less like mine, acquaintances, same age span, with undiagnosed but suspiciously alike husbands. Silent avoidant men with some eccentricity, depression, anxiety and little visible action about them. Frustrated sad stressed out women. 

There is an often told story about men who leave their wives for younger women. But we know the vast majority of marriages end when women ask for divorce. Both patterns seem to speak the same language of disappointment. A woman wanting to get out at all costs. A man craving acceptance from a woman who doesn't know him.

Maybe I'm way off the mark here with anecdotal evidence, but I sense a universal theme. How underdiagnosed might this condition be? They now believe it might be as much as 15% affected boys and 11% affected girls in my country. Some people don't qualify for diagnosis later as adults. But still. It's a lot.

My heart aches for both spouses in this painful dynamic.