In both cases he should maybe seek therapy. Maybe his mental development stopped somewhere in his own teenage years and connecting with a 19yo is easier for him. He could do a lot lot worse then dating a 19yo. Maybe he is attracted to teenagers or even pedophile, but it's not like he can do anything about it. It's undoubtedly creepy behaviour on his part. I'll probably get downvoted to oblivion, but let's play devil's advocate.
