Was it my fault.

I was talking to this guys for a month. First two weeks it felt like he was rushing things so fast but I was fine with it. We were already going on our first trip together to the poconos and sleeping with each other. But I did know that it was only 4 months that he had gotten out of a relationship of 5 years but I guess I didn’t mind. Around nov he ended things with me out of nowhere since we weren’t ever official but a little fling I guess and now I see he went back with his ex of 5 years.😑😐 . I’m assuming he still loves her and was just using me to forget her. But was it my fault that I was too easy? Do you guys think I meant something to him? I mean he would post me on his Instagram but I feel dumb now