He says “I love you” only when he’s getting fucked

My husband only ever says “I love you” when I’m fucking him. I’m not being sarcastic... he literally says it only when we’re having sex. Do you think he’s just in it for the sex? We’ve been together 3 years and in the beginning he would say it without sex but now he’s stopped. He says I love you right when he’s about to cum in me...