WHY ARE GUYS SUCH JERKS??

WHY ARE GUYS SUCH JERKS??
That is a simple question and it deserves a good answer. So I figure that I might as well tell you the reason that I ask that question. The story behind it.
Okay, here it is. So I've been in love with this guy who I have dated before. He told me that he liked me and all that stuff that comes along with it. And I believed it all. So I gave him a second chance. Well more like a tenth chance, but who's counting?? So we talked back and forth for about two weeks. In those two weeks he had almost earned all of my trust. Then he just stopped talking to me all of a sudden. And no matter how much I tried to start a conversation, it never was returned. It had been like eight days and we had yet to talk. So I sent him a text explaining just how annoyed and hurt I was about the situation. He never replied back. Again. So about three days afterwards, we talked. At four thirty in the morning. I was pissed but happy that I wasn't completely out of his life. So I thought.
We get back to school and I find out that he might have a girlfriend. What the hell??? This shall be continued..................