I have literally NEVER seen anyone go loco about a 19 y.o. and a 25 y.o. It's never happened... 19, and 40-50 yes, and too damn right. It's a power imbalance, and very weird. What on earth can anyone of 40 to 50 have in common with a fucking teenager? 
I know, right now, a young woman who is 26 who is dating a 58 year old man. Everyone she knows is creeped out and freaked out by it. His 2 CHILDREN are older than her. And he has a grandson who is only 10 years younger than her. Her parents are refusing to speak to her, and most of her friends give her a wide berth or are worried for her. Her colleagues are worried for her too.
She is 26, and looks like/dresses like a 60 year old woman would have dressed in the 1970s. She looks middle aged, gaunt, and never goes out with her friends, or mixes with her peers anymore. She is his handmaid. She does all his life admin, and his housework - even though they don't live together, and she and he have their own individual flats. He drinks (too much) and she buys him 1 or 2 bottles of vodka or brandy every week. When he says 'jump!' she asks 'how high?' It's an utterly bizarre and toxic relationship.
So yeah, people do get funny on here about age gaps where the older one in the couple is old enough to be the younger one's parent - or grandparent!!! But there is a reason for that. It's weird, and it's wrong.