The third error leading to the assumption that there is nothing to be learned about love lies in the confusion between the initial experience of "falling" in love, and the permanent state of being in love, or as we might better say, of "standing" in love. If two people who have been strangers, as all of us are, suddenly let the wall between them break down, and feel close, feel one, this moment of oneness is one of the most exhilarating, most exciting experiences in life. It is all the more wonderful and miraculous for persons who have been shut off, isolated, without love.
This miracle of sudden intimacy is often facilitated if it is combined with, or initiated by, sexual attraction and consummation. However, this type of love is by its very nature not lasting. The two persons become well acquainted, their intimacy loses more and more its miraculous character, until their antagonism, their disappointments, their mutual boredom kill whatever is left of the initial excitement. Yet, in the beginning they do not know all this: in fact, they take the intensity of the infatuation, this being "crazy" about each other, for proof of the intensity of their love, while it may only prove the degree of their preceding loneliness.
This attitude — that nothing is easier than to love — has continued to be the prevalent idea about love in spite of the overwhelming evidence to the contrary. There is hardly any activity, any enterprise, which is started with such tremendous hopes and expectations, and yet, which fails so regularly, as love. If this were the case with any other activity, people would be eager to know the reasons for the failure, and to learn how one could do better — or they would give up the activity. Since the latter is impossible in the case of love, there seems to be only one adequate way to overcome the failure of love — to examine the reasons for this failure, and to proceed to study the meaning of love.
excerpt from: Erich Fromm (1956) The Art of Loving.
pdf: Falling in Love