Feel gutted about the actions of a friend, advice and can anyone relate?

I struggled to make friends at school. When I moved to college three years ago, things began to get better, and it started with one particular person who was the first person I'd formed a closer friendship with in either school or college. For that reason, the person is special to me, and the friendship means a lot. We've stayed pretty good since then, but recently I saw that he did something that I'm really not happy with. I don't want to go into it (and I don't really want to talk to him about it), but it makes me think about him in a different, more negative way, and unless he changes as he gets older, I can't see our relationship being the same. I've made other friends since him, but I've not felt the same excitement and pleasure about anyone else. I'm really struggling to deal with the fact that it might be drifting away, and not carry on the way I wanted it to.
Also, we became friends through writing and drama, and I like collaborating with him. I've got an idea for something that I wanted him to be part, but this (alongside his unreliability, even though that's not a personal thing) could make it difficult or impossible to work with him right now.
Can anyone relate to the feeling of one person feeling especially important to you, and how to deal with them letting you down, or the relationship becoming less than what I wanted it to be?
  • Having autism and Attention deficit disorder making friend and maintaining them is difficult. If your friend is not on the spectrum their is a chance he has just out grown you because we develop mentally and emotionally at a slower rate than the typical person.

    For example I'm  twenty four and mentally because of my issues i would say mentally i am around sixteen mentally and emotionally i might catch up with the rest of my peers of the same age or i will constantly lag behind them and that is okay. most of my friends from high school i have lost touch with for that reason and the others i personally don't want my issues dragging them down.he might just be pushing you away to protect you from their negative situation, I have done this so many times people.

    But their is that one friend who i met in college with similar issues to me and even though we don't see each other physically that much we text and call each other at-least once a month because scheduling difficulties and the fact that i forget. Because i am forgetful my friend gets frustrated by accept that my brain is built differently. 

    Honestly ask them straight up if they actually want to do the project with you or is their something else you can do together instead would be a start. Is their anything that may be making him unreliable like any barriers such as health issues, transportation or other obligation such as work that may stop them from participating.

    If he has done something that you disagree with,the only way you can deal with it is to stop being silent and talk to them about it because it will develop into something bigger or be brought up eventually at a later date.  

    Is this relationship just Platonic friends or is their feeling of more romantic because if its Platonic friend i can totally relate too.