Cassandra Clare said this quote

She had worn the Morgenstern ring since Jace had left it for her, and sometimes she wondered why. Did she really want to be reminded of Valentine? And yet, at the same time, was it ever right to forget?You couldn't erase everything that caused you pain with its recollection. She didn't want to forget Max or Madeleine, or Hodge, or the Inquisitor, or even Sebastian. Every moment was valuable; even the bad ones.