Why Am I This Hurt?

Just ended a relationship of 6 months, the dumping was mutual, we were getting nowhere, I was being fed breadcrumbs, and she innitiated the dumping making my job easier. Nevertheless it was what I wanted, and now that it has ended, why am i this sad? I probably got attached since my last relationship was 4 yrs ago. At the end of the day I know I will recover from this and grow, but why am I this sad? Damn human beings.