Yeah. 4 years apart in a relationship is really nothing once people hit a certain age. 17-21 though? 17yr old me was light-years away in experience and maturity from 21yr old me. You are talking high school junior/senior to college senior about to enter the workforce. And as a guy, ignoring the minor status, I don’t know any 17yr old girls who are mature enough or have the life experiences to even interest me. They are high school girls, for goodness sake.
It always depends on maturity and some people are more mature than others. 17 though, I’d give the 17yr old some time to figure out who they are outside their parents and school…