How do I prove that I'm crazy about him?

A relationship is all about trust and communication. Something is not right here if you are saying something very clearly to him and he is saying “Nope, you’re lying to me.” In essence that’s what he’s saying. You should NOT have to prove your love to him. You’ve already told him and undoubtedly shown him through your words and actions. If he refuses to believe it and wants you to start jumping through hoops, it sounds like he’s insecure and can’t believe that he is worthy of someone caring that much.

So assuming you do show your love for him, you need to sit down with him and discuss this. Love is a very personal, very communication-based thing between two people. It’s based on respect and trust. Ask him why he doesn’t trust you, why he doesn’t believe you, and what he feels is wrong with the relationship. And listen to his answers. This is something you two need to work out now. But if it comes down to him insecurities, that is something he needs to work on. Love isn’t about doing great deeds. It’s about being open, being honest, being reliable, talking and sharing. And for him, it’s about believing in you.