My dad, who is divorced, tried to sum up his marriage advice for me: "Marriage can work if each person is willing to contribute more than half to the relationship."

Now that I'm married with three kids (one a teenager), I think he might actually have been on to something. Life isn't fair, things probably won't even out in the end, and nobody will ever fully appreciate the thousand invisible things you do to make your family work. If your belief system expects the opposite of those statements to be true, then you might not allow yourself the emotional slack to buffer the incredible variance of a marriage that lasts long enough to cover the normal trials of real life (illness, death, job change, envy, jealousy, in-laws, travel, aging, boredom, financial trouble, etc.).