I think 19 is still a teen so that makes it weird to me. If they had that same age gap but the guy in mid 20s and the girl around 30 I would think nothing of it. A girl at work was 27 and her boyfriend 19, but they'd been together 2 years. It seemed odd to me, an adult being with a child. I feel the same way with the guy being older too. When one of them is so young it seems somewhat icky.