Max age a 17 y/o can date

So I'm 17 obviously, and recently I've been talking to this guy that is 21. We're both clear this isn't all about sex. (Actually not anywhere near sex for a long time for sure.) I do turn 18 in January and I'm assuming it won't be as big of a deal then? But a few months after I turn 18 he'll be 22, and honestly I think that's fine. I'm asking because my friend is like, "that's really weird.." But I think she's being an asshole. Opinions please? Comments? Concerns?