Situations such as these are tough to deal with. When I have dealt with that, I bring people to the table and have hard, uncomfortable conversations. I make space where they can unload and say what needs to be said (this assumes both parties want to reconcile). I will typically give them Biblical wisdom in a manner that is palatable for them; I may not quote the verse # or chapter. However, they will get the same knowledge and wisdom. I do this because If I were to go in and say "the Bible says" or "Proverbs 20:21" says, that would shut them off to be able to hear anything else from me.
Other times it is only 1 party who wants to fix things and bring about a change. That's okay because you focus on guiding them and giving them tools to use to navigate the situations and tensions between the other offended party. Forgiveness may need to take place, and I will add that even if the other party doesn't ask for forgiveness for the wrongs they've done, the other party can still forgive and release them from that. This helps combat anger and bitterness from taking root in the person who has to forgive. Once you stop forgiving you stop growing spiritually. Finally, some clear and healthy boundaries may need to be established so everyone involved
