It's circumstantial- though something I enjoy about our differences is being able to face conflict as opposed to running away from it. I believe like any muscle, it takes a bit of practice or training to develop. Same can be said for tolerance, meditation helps us recognize conflict as it arises in our minds and bodies- it may even help us take a moment before caving in to repeated or undesirable behavior.
Then there is the option of letting it be- not because one is afraid of conflict-resolution but because there is no healthier outlet available. Recognizing something as outside our power and making peace with it. I have been accused by others, and sometimes I am able to see the emotion behind it and better understand where the person is coming from. Whether I have the insight or not, it has proven beneficial to walk away, even if only temporarily.
Whatever happens, happens. Who am I to say where you or another are in their journey, and what is important for you?
I think people actually need time from us to introspect about how they have treated us and we have treated them. In this case what you called letting it be. Although we do have methods of our own that may not be as passive as the term ‘ letting it be ‘ implies. Most people are not so experienced in introspection so they react to outside circumstances. If they are able to, they move on to another person or different circumstances that are either conducive to understanding or only duplicate problems in relationships. I would agree though that if possible it may be better for us to walk away from the situation temporarily and in some cases on a more permanent basis. I think we often need time alone. It is just that we are so attached to outer stimulation that we find it difficulty with spending time being alone.