Genesis 24:67 says that Isaac took Rebekah, she became his wife and he loved her: "Then Isaac brought her into his mother Sarah's tent, and he took Rebekah, and she became his wife, and he loved her; thus Isaac was comforted after his mother's death" (Genesis 24:67). Notice the order. This seems backward to us. We would expect the opposite. In our culture, we believe that a person should marry whoever he or she falls in love with. Isaac married his wife, and then he fell in love with her.
Isaac took his bride into his mother's tent. All this time Sarah's tent had been empty and forlorn, symbolizing the absence of the eishet chayil (virtuous wife). The Torah portion began the story of Rebekah by telling us of the death of Sarah. Since his mother's death, Isaac had been in mourning. He keenly felt her absence. Isaac taking his bride into Sarah's tent symbolizes Rebekah stepping into Sarah's role as matriarch over the house of Abraham. In the language of the rabbis, Rebekah became the house of Isaac.
Abraham loved Sarah, and Isaac loved Rebekah. Genesis 24:67 says that Isaac took Rebekah, she became his wife and he loved her. Notice the order. This seems backward to us. We would expect the opposite. He should have fallen in love with her, married her and then taken her into the tent. The Bible has a more sober (but no less romantic) view of marriage. Isaac did not marry Rebekah because he loved her; he loved Rebekah because he married her. Considering the folly of the human heart and the fickle ups and downs of emotions, this is the proper order of things. We should love our spouses because they are our spouses.
Love followed be marriage seems like the natural order, but it's a bad plan. It is possible to fall in love with the wrong person. It is possible to fall in love with many wrong persons. Falling in love is a terrible criteria upon which to base a marriage. It would have been easy for Isaac to fall in love with any number of Canaanite girls.
As children of Abraham and followers of Messiah, we are to love our spouses. Paul tells men to love their wives as themselves—and more than that, to love them as Messiah loved the assembly. He warns husbands not to become embittered against their wives. It's not a matter of the whims and inclinations of the heart; it is a duty of every husband to love his wife.
If a man or woman bases his or her marriage merely on love, it is doomed from the start. Feelings are unpredictable. They rise and fall. They come and go. Marriage must not be based upon love. Love must be based upon marriage.