Have you ever dated a younger guy?

I've been talking to a 19-year-old guy for a few days, at first, we were just like friends sharing our thoughts and life experiences. But now, he keeps texting me, wanting me to talk to him, I feel so weird, I was never into younger guys. He is a nice, friendly and mature guy compared to most of the boys of his age. And I don't have any such kinds of feeling for him but I think he has something like that in mind. Btw I'm a 21f.

Should I stop talking to him?