‘Relationship going bad’ is a euphemism really, and it does not really clarify what is going on. Relationship going bad means the minds of the two people in the relationship are bad. A bad relationship fundamentally indicates a bad mind.
And if their minds are bad, it is not only this one particular mutual relationship that would be bad; all their relationships with all possible conceivable objects in the universe would either be bad or waiting to show up as bad.
What is a bad mind? When I say a bad mind, I am not talking in the sense of morality or ethics. A bad mind is one that does not know itself. A mind that has no self-knowledge is a bad mind. A mind that is obsessed with the world and its enthralling objects is a bad mind.