Hanif Kureishi said this quote
“ If you never left anything or anyone there would be no room for the new. Naturally, to move on is an infidelity -- to others, to the past, to old notions of oneself. Perhaps every day should contain at least one essential infidelity or necessary betrayal. It would be an optimistic, hopeful act, guaranteeing belief in the future -- a declaration that things can be not only different but better. ”