In any relationship, there will be frightening spells in which your feelings of love dry up. And when that happens you must remember that the essence of marriage is that it is a covenant, a commitment, a promise of future love. So what do you do? You do the acts of love, despite your lack of feeling. You may not feel tender, sympathetic, and eager to please, but in your actions you must BE tender, understanding, forgiving and helpful. And, if you do that, as time goes on you will not only get through the dry spells, but they will become less frequent and deep, and you will become more constant in your feelings. This is what can happen if you decide to love.
— Timothy J. Keller, The Meaning of Marriage