Friend breakup heartbreak

There are many types of heartbreak:  the death of a loved one, the repeated disappointment you feel from questionable actions of a loved one, breaking up with your significant other, when your significant other leaves you...   And then, there's the heartbreak that stems from losing a close friend.  You thought the two of you were close, and you were enjoying, or wanted to enjoy, continued closeness with this person.  But it turns out they aren't interested in that sort of relationship with you any more.  Their motivations are dictated by shiny, new experiences, and, frankly, your presence in their lives has ceased to be important or a priority.  It's shocking, and yes, heartbreaking.  

I remember the first time I was heartbroken like this.  I was in 2nd grade.  I went to a Montessori school where 3 grade levels of children shared a classroom.  Sarah Shannon, who was a sweet chipmunk-faced 4th grader, and I had befriended one another.  We spent every day sitting on our mat, doing our work, and talking about whatever 2nd and 4th graders talk about.  I spent the night at her house and felt very grown up being her friend.  Then, one day, she didn't want to share a mat with me any more.  She wanted to share a mat with Marcie Schenck instead.  She invited her to spend the night and didn't even say goodbye to me at the end of the day.  I was devastated.  

I spent the evening gathering some peace offerings:  two tiny plastic rabbit figurines I had recently gotten for Easter, and tiny vial of rose water, and a die (as in dice).  Tiny things were my treasures, and I was going to offer Sarah, not one but BOTH of my newest tiny prized possession bunnies.  I hoped that my offering would help her see how much she meant to me, and that she might reconsider, and decide that I could at least join her and Marcie at their mat. 

The next morning, when my mom dropped me off at school, I remember she had to pull over and talk to me because I refused to get out of the car.  I sobbed, slumped down all the way in the back seat, miserable.  I was so embarrassed to be just a little 2nd grader, whose friendship, I inferred, was not nearly as good as Marcie's 3rd grade friendship.  I was so embarrassed that I had pretty much considered a 4th grader my peer.  How could I have been so dumb? But also, why didn't she like me any more?  I was too embarrassed to get out of the car and walk into my classroom like nothing was wrong, when I knew I'd be sad all day long.  Eventually my mom talked me into going into school, walking me in herself, at least 30 minutes late (explaining to the teachers in discrete terms so that they wouldn't draw attention to my predicament, and so I didn't get in trouble for being late).  I gave Sarah my little bunny figurines, and I don't think the gift registered at all with her.  And that was that.  I sucked it up, and had to move on.  But it left a scar on my heart.