If you hold back on the emotions--if you don't allow yourself to go all the way through them--you can never get to being detached, you're too busy being afraid. You're afraid of the pain, you're afraid of the grief. You're afraid of the vulnerability that loving entails. But by throwing yourself into these emotions, by allowing yourself to dive in, all the way, over your heard even, you experience them fully and completely.
I choose to be just your friend because I'm afraid that if we go further it will not work and the friendship we had might be gone.