Is it normal to want what you don't have and never learn from it?

My bf and I went our separate ways which was his idea. So we broke, it was def difficult for me to move on but things were starting to look up. However, my bf continued to reach out to me. I was actually pretty proud of myself at how I never gave in a contacted him first or replied right away. He was the one to always contact me and in a relationship way like we were still together. Eventually, we planned to see each other and he was so excited about it. I loved it. I was like where has this guy been this whole time? So we met up, hung out, and in the end decided to give it another shot. Well now that we're back on, hes acting in a distant way. Hes not reaching out to me like he was when he didn't have me. He obviously went through the case of "you dont know what you have until its gone." He missed me and was really open about it. And now that he has me again, hes not putting much effort. He leaving me hanging when I contact him, hes barely talking to me. Why does it have to be this way? I know for a fact that if we called it off again, he would come back chasing me like he was before. Why can't he just appreciate me when he has me and not take me for granted? Why does he have to be into me when he doesn't have me? Its pretty common but I noticed its pretty common with guys and its pretty common for the dumper to do this as opposed to the dumpee.