Someone treating you like you don’t matter is all the closure you need. You don’t gotta keep asking what changed, trying to fix it, or waiting for them to act right. How they handled you already gave you the answer. Once somebody makes you feel unimportant, fall back and move on.
Your partner will affect your nervous system, your choices, your sleep, and your beliefs. If they can’t take responsibility for the energy they bring to the relationship, you won't have peace in your life.