Honestly, and I wish this wasn’t true, a lot of people do this. Once they find someone they like or even love, they go back and remember all the good times about their past relationships. They remember how that other person made them feel, and then they compare it to how the person their with makes them feel, and if it’s the same, not necessarily worse or better, but the same feeling, they romanticize the past. They think that in their memories, the other person made them feel more or better or happier than the person their with currently does, even if it’s not true. I would tell you that you shouldn’t leave your boyfriend for your ex. It won’t be as magical as you imagine it to be and people will just end up getting hurt. If you realize you don’t like your boyfriend, then break it off, but don’t do that because you think your ex will treat you better.