the relationship may have been great for you, but maybe it wasn't for him. you haven't been able to move on as fast as youd like because there wasn't really any closure. here's th ething: not everyone is going ot give you closure, your best bet is to take things slowly and do it at your own pace. make sur eyou have friends around, ones that won't bring back memories of him, meet new friends, maybe start a second job to pass the time and its alwasy a great way to meet new people. or get one if you don't have one, anything to pass the time. try starting a new TV series, again anything to keep him off your mind. go out, have fun, meet guys and give htem chances, but again at your own pace. the only cure to your emotions right now is time and time it will take. just keep your head up and try to start the process of moving on, he hasn't given any indication as to why you broke up or that he's interested in trying again. if its meant to be it will be, but you don't want to miss out on any chances you may have to find a better guy that will treat you the way you want to be treated.
It went "great" for you maybe but him...nope! Why do you need to have answers from a douche that just up and left? I went through the same thing a month ago and I say good riddance to yesterdays trash.
Not being given any answers is an answer within itself. As annoying as it sounds he might not HAVE an answer, or one that would make enough sense or seem decent enough to break up over. Trust me, I was in the same place 6 months ago. I know people will say "Maybe the relationship was great to you, but not for him and that's why" but you know you deserve someone willing to work it out or be up front with you - not just up and leave out of the blue! Try not to focus on the "whys" of the past. Even if he called you this minute and told you "why" it wouldn't change anything and most likely wouldn't give you the satisfaction you think it would. And don't be so hard on yourself for missing him. I still think about my ex every day, although the intensity of emotion has changed-he was important to me and I can accept that and still move forward. And No Contact can be hard, but I really think it's for the best.
You sound as though you never got any closure from the relationship, you never got any answers or an explanation, so in your head nothing makes sense for why it ended, which is why you can't let go. All I can say is, in time you will get over it, It may take a while, I have missed someone for a year and a half before I felt as though I could really genuinely learn to love someone else. That is really the only option you have, to just wait it out, because you can't ask him for closure or an explanation now. You've already come so far, four months is a long time, to talk to him again would just make it hurt more. So get out there, distract yourself, perve on hot guys, flirt with them, improve yourself, and before you know it you'll think of his name and not miss him anymore.
You think it was great dear but if you think deep, or preferably, ask your ex what went wrong you'll find out that it wasn't great. The two of you need to talk about it. It doesn't make sense to just break up with someone for no reason.