Guys, (and Girls), Why is he not showing any interest in carrying on the conversation?

I am, admittedly, normally the convo startd, but I have backed down lately on purpose. Well, my crush texts me "hey" and we text a lot but I normally start so I was excited. After that, he showed no interest in continuing the conversation. I know he got/opened my texts. I badgered him a bit. I don't understand how he could start it but not have any interest? Guys, why would you do that? Girls, has this happened to you?