The Baal Haturim tells us that when Rivka came into Yitzchak’s tent as his wife, he loved her. This was true love as it was not based on anything physical or material. It was a deep, lasting love.
Rabbi Avraham Twerski, who was also a psychiatrist once wrote why marriages fail. He said that the main reason is that the marriage starts out badly from the start. It is based on, “She says that he has something that I really want, and he says that she has something that he really wants.” When that something is no longer relevant, the marriage falls apart.
The example of Yitzchak and Rivka is that they shared common spiritual goals. These goals never get old, and they establish a partnership that lasts a lifetime. The physical and material are fleeting. They can easily become stale with time. And certainly, a common lofty goal, is the joint effort in raising children in the path of the Torah. When couples work diligently towards this goal, it helps solidify their bond as well.
Again, the Torah in its own subtle way, gives us lessons that are very valuable. This is the purpose of the Book of Bereishit. We are to learn from the examples of the Matriarchs and Patriarchs.