What might cause younger guys (<25) to have trouble staying erect, and how do you think women should approach it in the moment?

I’ve noticed that the last few partners I’ve been with (all under 25) have had some difficulty getting/staying hard. Trying not to get too in my head about & want to ask: is this something that’s common for men in that age group, or is it more of an individual issue? How would you prefer a woman to handle this situation in the moment if it happens?