Trust, loyalty and honesty is what we have to maintain despite everything we can face in a relationship; it doesn't matter what kind of problems one person has with another, I think it isn't necessary to lose them, what do we get if we do not maintain it?... If someone puts their trust in you, it is because that is important for themselves and because you are also important for them and we, as a good friend, always have to be frank without worrying if it sounds hard . That's my point of view about the main key for a healthy relationship. Please correct me if I have any errors.