I am having a hard time understanding what/when/why it went wrong. He gave me a very vague explanation as to why he was breaking up with me and I just don't know if he is telling me the full story. Knowing why he broke up with me will help me move on instead of waiting around hoping he will come back. (which is what I've been doing :/ )

I am very sorry if this is going to sound harsh, but he broke up with you. You don't really need to know the science behind being shot by a bullet to understand there is a wound. And just like being shot [non fatally] it takes time to heal.

He does not owe you closure. He ended the relationship, he is not going to get back together with you. I am not sure why you are waiting around after three weeks for a guy who didn't give you the courtesy of a real conversation.

How do I talk to him about how I feel and get closure without seeming desperate to have him back? I don't want to overstep my boundaries and end up pushing him further away. Any and all help is appreciated thank you :)

But you are desperately hoping to get him back. You said it yourself.

Knowing why he broke up with me will help me move on instead of waiting around hoping he will come back. (which is what I've been doing :/ )

You want him to explain why he broke up with you so you can fix it. I have seen this game played a thousand times, by both genders. I have even done it myself. The closure comes from time, from realizing that one door closed does not mean you're locked away forever.

What you really want is for him to take you back, because you don't think you did anything wrong in the relationship. You have not had the time to come to terms with the relationship and to grieve it. Right now you are thinking him being vague means he didn't have a real reason to break up with you and hoping that making him explain it will solve the issues he has.

You might promise to change, to really make him happy.

Don't. Have some dignity. I am sorry if this is harsh, but I went through this with a girlfriend. She didn't understand why I didn't want to keep dating her. I just lost affection, I didn't feel it anymore. It was hard to explain. She kept coming at me again and again and I finally told her the harsh truth.

She bothered me, she chewed with her mouth open. It was like listening to a cow chew. I hated her shows. I disliked her best friend. All the quirks I thought were cute were not killing the relationship one nail in the coffin at a time.

I stopped feeling like we were a team. She was distant and grumpy. I am far from perfect, but she didn't seem to respect me anymore. She rarely asked what I wanted to do. She just decided for us. She wanted us to lose weight together, but then said it was mostly me she wanted the weight off of--despite her being heavier--and it just... didn't work anymore. I didn't love her.

So I wouldn't ask for the truth. You have been given all you need to know he does not want to be with you. Ending the relationship is all the cause he needs to give.