21-17 while bad isn’t that horrible because they could have went to school with each other. Like a Senior and Freshmen in high schools isn’t great or a senior in college and freshmen isn’t great but it’s not that bad.
Considering this board can't figure out what a 41yr old in Terrance J and his 25yr old fiance talk about or have in common...pretty sure 17-25 is about the same age to the board.
All that being said...many a high school girls sneak into frat parties and college parties at about 16 once they got licenses. I remember some peoples high school aged siblings hanging out at college from time to time. I doubt much has changed from what I saw 15-20yrs ago.