Marriage is not comfortable and harmonious. Rather it is a place of individuation where a person rubs up against oneself and against the partner, bumps up against the person in love and in rejection, and in this fashion learns to know oneself, the world, good and evil, the heights and the depths.
The indigenous peoples of the great tourist spots seem to lose their souls. All cultural, religious, and political efforts and ideals are crippled since the culture is engaged only in luring ever more tourists. It is not the contact with an essentially foreign population that corrupts the inhabitants of the great foreign resorts. It is the contact with great masses of people who are seeking fir the moment only well-being and not salvation that weakens and devalues the indigenous population.
A marriage only works if one opens to exactly that which one would never ask for otherwise. Only through rubbing oneself sore and losing oneself is one able to learn about oneself, God, and the world. Like every soteriological pathway, that of marriage is hard and painful.
For those who are gifted for the soteriological pathway of marriage, it, like every such pathway, naturally offers not only trouble, work, and suffering but the deepest kind of existential satisfaction. Dante did not get to Paradiso without going through the Inferno. And so also there seldom exist "happy marriages".