It Went From Me Being "The One" To Him Never Wanting To Be With Me Again

This guy and I had been dating for a few months and everything was great up until the last couple weeks where we started arguing every couple days about things we thought differently about. We would make up and come to a compromise fairly quickly though. I was the first girl he had done so many things with, like staying the night and showing baby pictures to and generally making a legitimate commitment to. He left one morning to go to class after we had an argument the night before and kissed me goodbye then texted me to say he didn't think he could do it anymore. He then proceeded to avoid me for three days with no explanation and I went a tad overboard with constantly calling and texting him and even walking to his house to try and get an explanation. On the fourth night he came over and said he didn't know why he was doing it but that when shit hits the fan he just runs. He hugged and kissed me for the last time but said he wanted us to get back together in the future after he figured things out. We didn't talk for a week and then I messaged him and he said he had been thinking of ways we could hang out and have that cute friends stage we didn't really have because I was in Ohio for school. After that we had one more conversation and then a day later some random guy messaged me saying my ex and his sister were talking. I confronted him and he said they were talking and that he found himself in the nearly three weeks we have been apart and that he doesn't want us to get back together ever again but that he would love to hangout and be friends. I believe him and another girl, a really close friend of his, are now hanging out as well. I bought her a Plan B pill right after I got home for break and now she is singe and they are liking all of one another's posts on Facebook and her and I are like the same person mentality wise. My questions are, is either girl a rebound purely for the attention they are giving him or has he been wanting to get with this close friend and was settling for me? And if that is the case then why did he tell his mom and everyone that he knew I was "the one"? How did everything change so quickly and should I be his friend and wait for an opening to get him back or should I do the no contact ordeal and make him miss me? Is there any hope that we will be together again?