Age differences

So I had a friend that I liked, and he liked me at a point. Sounds okay, right? The feelings mutual, or so I thought. He is 15 and I am 13. Okay so this is where it kinda hits me in the face. He said that he does like me but i’m too young. First of all, my 4 best friends are all 18 and happen to not even think of me as a 13. Second, it’s just 2 years. So there’s that, BUT THEN YOU HAVE TO THINK. The younger the person is the closer the age should be. Doe’s that make sense. If I, a 13 year old, were to date an 11 year old, that would be kinda weird if you ask me. So is it the same situation. If you think about the whole “Highschool boys don’t just wanna hold hands” thing, I’ve already talked to him about that and it’s like his biggest fear. SO WHAT IS THE PROBLEM!!!!!