I think I get it. Tell me if I'm wrong, though, because I'm extrapolating from my experience.

You got something from her, from being with her. And then she badly hurt your feelings and disappointed you by double-booking and the slow texts and trouble finding an appointment time. It's like she filled a lack or a void in your life that you didn't know you had. And then she messed up and it was intolerable and so you quit. But now you feel the void. Sucks!