A marriage is a great container of commitment, like parenthood, for people to discover lots of stuff about themselves they don't like! That is good news, really, if two people are on the same wavelength. Marriage can be a compassionate laboratory in which each person faces irritations, annoyances and disappointments rather than ignoring or resisting them. Breakdowns in tasks involved in having a home, a job and a family - the details and decisions that need to be made every day - do not have to be interpreted as "something is definitely WRONG here," because problems present valuable lessons in such marriages.
A spiritual context of marriage as "practice and path" provides freedom to be oneself. You don't have to hide. Since anything that happens inside this sort of partnership is held as grist for the mill, nothing is wrong or "should not be that way." When a couple declares that their marriage is going to be a vehicle for their personal growth and service to others, everything that would have seemed an insoluble problem is now mined for the gold of increased self-awareness and compassion.
Here's a sweeping statement for you: a lot of (most?) marriages are invested in providing the two people with comfort, nurture and a shield from all the bad stuff in the world. This is often the hidden, unconscious and unarticulated purpose. Love songs affirm fairytale marriages in which individuals find one another when each cannot stand alone: "I'll never be lonely if you love me." "You are the reason for me to live." "Loving you has brought light into my dreary life." This sentiment causes mischief; we all hear this junk so much that we believe this is real love. The fact is that thriving marriages have periods of loneliness and sorrow and loss that each person may have to address separately.
Desiring comfort and nurturance from your primary relationship is entirely natural and predictable. Marriages that are focused only on comfort maintenance are not terribly satisfying, however, after the first year.
"Hold on there a skinny minute," you say. "What about couples that argue all the time? They are not looking for comfort! They are miserable." If you know two people that bicker constantly, it is most likely a familiar, recognizable, though unsatisfying dance for them. Each person knows the steps, after all; there are no surprises, no creativity.
A couple committed to their marriage as a spiritual journey eventually will ask questions: what is driving these arguments? What are we doing? What are we hiding from? Are we trying to avoid intimacy? The partners will intentionally inquire into the places in which they are not free. These are the kinds of questions that are natural to a marriage-as-spiritual-journey.
The journey of the committed couple can be full of very, very difficult problems that threaten to defeat it but which do not have to. As a couple faces and works through their challenges, the marriage does not just get through "a bad patch," the marriage becomes a vehicle for tranformation as two people become more loving, unselfish and other-directed.