Most Helpful Guy
Instead of focusing on getting your ex "back", focus on getting "your" life back.
As these wise people commenting before me have stated, all you can do is respect what he's told you. I believe if you trust giving yourself a bit of time, you'll eventually come to realize he was doing the both of you a favor in ending things. You two weren't getting along, and you can't blame yourself, because it takes two, so it was NOT all your fault.
I've been in situations where initially I would have done or given anything to return back to Happy land with the woman I thought I loved beyond life itself, but when the other person is done, you ultimately have to accept nothing you can do will change their minds. If a change of heart is made, they have to do that on their own.
Why do you have to keep your shit together and not him? As I said, I don't think you living in a convent is going to get him to come running back to you. Today is what matters, and today he doesn't want to be with you anymore.
I do think working on yourself is a good idea, but for reasons other than turning your ex's head. Time will allow you to see your relationship with him more objectively, and if you really feel there were things you did that pushed him away, then work on changing them from within yourself, which will help you moving forward and in future relationships.
Also, think about some of the shit things he did that you did not like. I'm sure he's no saint either, and there's most likely times he provoked arguments or did or said things you weren't happy about. Time will reveal more and more of that and the waves of happy love will start getting smaller and smaller as reality sets back in.
Don't beat yourself up and if you can't stop obsessing over something you have absolutely no control over at this point. The only thing you can control is yourself, so take some time, grieve, reflect and allow yourself some time to heal, because you won't start feeling better overnight.
Try and occupy yourself with the hobbies you did before you met your ex and reacquaint yourself with the friends you saw less of when the two of you were dating.
You're going to be okay, I promise. But it's time to give him his space and let go.
Most Helpful Girl
I'm kind of in the same situation where my boyfriend said he's not in love with me anymore but still loves me. He's got a lot going on and is stressed and I think that contributes to it. Give him time and see what happens in a couple weeks. That is what I'm doing and just hoping for the best. It's hard to throw away something you've known for so long.