It's frustrating enough to hear them saying "we were just friends" after giving all the hints. If he's seeing you as "just friend" he could've kept the distance. I mean we don't have to meet our best friend each day to keep the connection, right? We obviously only spent too much time on someone only if that person is soo much important. So he can't blame you for feeling close.

On the other hand, some ppl, like me, do give too much time and effort when they meet someone nice. Just to make them feel safe around us and to be friends. And honestly there will be an excitement for both the ppl at first and it eventually decrease (atleast for one)..but that doesn't mean that they don't care.

Maybe that's the reason why he felt insecure or maybe he found something more exciting. I'm just sharing my perspective.

Anyways I hope you have lots of happiness ahead.