My boyfriend hurts me during sex.

My and my boyfriend are 17 and have sex on the regular. He is 6.5 inches long and 2 inches wide. Lately he has been going really hard in the bed room. It feels good at the time but in the morning or a couple hours after I am really sore. How do I tell him without hurting his feelings. This is the only way we've ever had sex so I don't know if that will alter our relationship. And I don't want to just give him bowjobs all the time just so he's not horny anymore. HELLPP!