The truth is that your relationship was over before it even really got started. You never treated it with the care and the thoughtfulness that goes into a relationship.
You have a very elaborate set of tests and trials to make sure that a potential partner is vetted. The problem is that you take such a long time trying to make sure that someone is okay enough to pursue a relationship with,
You didn't want to have "buyer's remorse" so you kept your options open with your partner.
He was honest from the outset and told you that he wasn't interested in having a relationship but you were convinced that once he spent time with you and got to know you, he'd change his mind. Only, he didn't.
You're too busy to waste your time on almosts and not good enough so you made a strong and healthy decision and ended things.
You both were at two different points in your life and you weren't connecting in a positive way.
You both were being so careful not to say or do the wrong thing that you weren't being yourselves.
Things got very intense quickly at the start of the relationship but then just as quickly they fizzled out. You shared an extreme sexual attraction for each other but very little else.
It didn't take long for your almost relationship to feel suffocating to you. You prize your independence and want to feel free to do whatever you please without feeling tied down to someone else.
You literally had no time to see him. You were far too busy to do anything besides the occasional text. You convinced yourself that if he really had wanted to pursue a relationship with you, he would have made an effort.
The two of you rarely spent any alone time together. You went on group dates with your friends and you never wanted to do couple things together.
You might not be aware of it but you acted as if he was some kind of mind reader. You expected him to know what you were feeling and what you wanted without ever saying anything to him about.