Jesus commands us to love one another. If we cannot love the person to whom we are married, how can we love the rest of humanity? Marriage between two Christians should be indissoluble as each gives up him or herself to Christ and the other. Most marriages that fail seem to do so because of one thing: selfishness.
And we are also advised to live in peace with all men inasmuch as it depends on us. Sometimes living apart is the only way to do it. Loving someone means wishing their good. It doesn’t mean pretending that someone with a bad habit does not have the bad habit.