Has anyone had a friends with benefits/hookup turn into a relationship?

I see this happening a lot these days. People having sex on the first date. A friends with benefits. A hookup.

But I’m curious: does anyone know anyone (or themselves) where this ever turned into something more, like a relationship?

I keep seeing people having sex and “going with the flow” with somebody they are seeing.

Im old lol and times have changed so just curious haha