"When people walk away from you, let them go.
Your destiny is never tied to anyone who leaves you, and it doesn't mean they are bad people. It just means that their part in your story is over.
We all have aspirations of being so extremely cool, that when we go through a break-up, instead of accusations and grievances, we instead merely murmur 'thanks for the memories.' But, of course, in circumstances such as these, there is hurt, pain, and anger and it's not often that you have it 'together' enough to be so cool. The first reaction is to fight for what you want and not ever give up. Not that this gets you anywhere, once minds are made up, there isn't often a change. You will wish you had handled it with a touch of class when the remorse sets in, but you are, after all, human.
This person wasn't meant for you, not permanently anyhow, they were just with you for the lessons. They wouldn't have left if it was a 'forever' thing. "Your destiny is never tied to anyone who leaves you." They show up, you show each other what you need to know, and they move on. Their time is up, and you are ready for something or someone new. You may not feel fabulous when they leave, but you will feel gratitude before long, as soon as you realize the growth that has taken place because they were there.
"Don't cry because it's over, smile because it happened." Dr. Seuss
Now you are ready for a new adventure, the door will open for another, either a lesson or the 'real thing.' This is life, a learning experience. You will touch many lives, and they you; and each time you will become a little wiser, more patient, more loving, more compassionate and much, much closer to the real you.