Lama Ole’s answer:
Like in other areas of life, the partners in a marriage want to have happiness and avoid suffering. In this respect, the marriage is no different from any other relationship between a man and woman—with or without the marriage certificate. Both partners are always free to do as they wish. But this changes as soon as children are born because they depend on their parents. When kids are involved, a couple should try to stay together, even though it might be difficult to find a common language at times. In this case, it would be better for the children to sometimes spend more time with the mother and sometimes more time with the father, as the children like.
Our attitude is what matters: we should support the other person’s growth and development, which means giving instead of taking or exploiting. To do this, we basically need to see our partner as something very precious, as somebody who is able to develop.