At first I was shocked and thought... what would a 23 yr. old want with a 16 yr. old, then I thought... that's not even legal, and then I thought.... Does she KNOW he's 16? Perhaps she suspects he is older since he is a junior and perhaps he didn't want to tell her how old her was because he was interested in her and wanted her to like HIM before he told her how old he really was? Not sure if that's a possibility but it did cross my mind. Not sure how long they have been "hanging out" but the fact that she was engaged and no longer is would make me question a few things. Did she break off the engagement because of you DS? Was she no longer engaged when she started talking to DS? I would definitely be skeptical. I would also step lightly on how you approach your concerns. Seeing as he does think on a higher intellectual level than his chrono. age, it's still a concern. Again, as others have stated, you are the parent and sometimes have to play the role of the bad guy vs. being a "friend" to your child. Find out what you can and go with your gut.