In the ideal partnership of love between two people all three forces have to be represented.
Marriage is intended by God for human beings and its divine purpose is not merely procreation. That is only one detail. The spiritual idea of marriage is to enable the soul to reveal itself and to be constantly on the search for the other to discover forever new vistas of the other being. The more this happens, the happier the marriage will be, the more firmly and safely it will be rooted, and the less it will be in danger of an unhappy ending. Then it will fulfill its spiritual purpose.
In practice, however, marriage hardly ever works that way. You reach a certain state of
familiarity and habit and you think you know the other. It does not even occur to you that the other does not know you by any means. He or she may know certain facets of your being, but that is all. This search for the other being, as well as for self-revelation, requires inner activity and alertness. But since people are often tempted into inner inactivity, while outer activity may be all the stronger as an overcompensation, they are being lured to sink into a state of restfulness, cherishing the delusion of already knowing each other fully. This is the pitfall. It is the beginning of the end at worst, or at best a compromise leaving you with a gnawing, unfulfilled longing.