My boyfriend will be 18 while I'm still 15?

So, I'm 15 right now and my boyfriend is 17. He will be turning 18 a few months before I am 16, which makes our relationship illegal, right? I really need some clarification and/or advice on this.
Update: We are not having sex, and we will not be for a long time. I can assure that.
17 answers 17