Live a life of love, just as Christ loved us. (Ephesians 5:2, NIV)
God uses relationships to make us more Christ-like.
Usually when problems arise in a relationship, we blame the other person. But more often, the reactions of the other person are a mirror in which we can see ourselves and our faults more clearly.
God uses these tough times to teach us and reshape us. He is giving us hands-on training in patience, forbearance, gentleness, and self-sacrifice. He is teaching us to set ourselves aside to make someone else happy, to reach out and understand the other person, even when they seem the most unfair.
Do you want the mind of Christ? He forms it in us through people. When painful, demanding situations arise, live love. God is doing a good work in you.