If someone disappears on you and hurts you, don’t give them an opportunity to come back. As nice as it is to hear them apologize in that moment, it can set you back. Most good people don’t disappear out of selflessness. There is something in it for them. If given the opportunity, the one who disappeared will think they can do it again. Who’s fault is it then if you allowed it to happen?
Same thing if you have to go no contact in order to heal and move on. This usually comes after closure of some kind between the two parties involved. If things have gotten so bad that you need to go no contact, keep NO CONTACT. One little slip and you can be back at square one feeling upset again.
Just my two cents.