I'm that age and I'd love to breed a person your age.... no need to be shy, trust me, he's finding every inch of you beautiful.
Nothing wrong with it as long as you're both having fun...... and older guys have benefits like being caring and having money etc. Relax and enjoy the ride to wherever it ends up.
As your ass gets used to fucking from now on it'll stop hurting and start feeling really, really, really good. Keep at it, it'll be like maximum a few more times until that happens.
I hope you're not using condoms? It's SO much better feeling cum squirt into your ass.... also, for reference, condoms cause his cock to be WAY less comfortable than barebacking it, skin on skin is going to be so less painful for you, you'll be amazed. So ditch the condoms and go unprotected.