The reason why scientists still have not come to a single theory of love and why there is so much confusion in comprehension of its essence is the prelogical thinking, which unfortunately boots in the heads of the theorists when they try to build their theory of love. As a result, they stubbornly try to cram all kinds of love having quite different origins and, therefore, different essence, into the single theory: romantic love, generated by sexual desire, love for God and a variety of attachments that arise on a different, not at all sexual basis. Moreover, into this list they often squeeze the sexual selectivity for the mating period among animals.The prelogical thinking continues to hold sway in the heads of scientists because until recently science, fulfilling a social order, was vitally interested not in clarification, but in confusing the issue of romantic love. Currently, the need for this confusion vanished, but the archaic ideas continue to persist by inertia. If you refuse of the prelogical thinking, if you do not try to jam into one theory of love the loves, having different origin, the theory of romantic love arises by itself, without much mental strain.The scientific theory of romantic love must first of all explain: why did it originate in human society? Why does it connect precisely two, and not a group of people? Why the mutual sexual drive inherent in this kind of love is so strong, and so great is the intensity of passions? Why does the idealization of the object arise? The existing theories do not provide the answers to these questions and do not even formulate these questions. The answers to all these questions are quite simple if you see the cause of the romantic love origin in the contradiction between sexual desire and the morality of the monogamous society. It is generally accepted that romantic love can be rarely found in real life. However, until the mid-20th century, it was the main theme of fiction. This also needs explanation and the explanation is as follows: numerous novels and films about love are not a mirror of life, but a means of ideological indoctrination of mainly the young people with the goal of creating an internal barrier that keeps them from extramarital and especially premarital sex, the consequences of which could be tragic for girls. Romantic love and jealousy are different phenomena, but in novels and in scientific works they are constantly connected with each other. In discussions of jealousy origin and, consequently, its essence, the range of opinions is extremely great. Two approaches are struggling here: the evolutionary-biological and the socio-psychological one. The first of them does not correspond to the facts, the second, giving an adequate explanation to some types of jealousy, ignores other types of jealousy or allows the simultaneous existence of several types of sexual jealousy of different origin. These shortcomings of both approaches are removed if we consider jealousy as a reaction to the violation of the rights established by law and customs as well as by the norms of morality in the sphere of relations between the sexes, wherein these rights can be a fictional, self-inflicted perception. Romantic love needs the obstacles. If the satisfaction of sexual desire between unmarried persons is allowed by the society quite freely, passions have neither fuel nor spark to flare up. That is why in future the romantic love will be met fewer and farther between both in life and in the arts. Sexual jealousy is a product of monogamous morality. Today's sexual morality has changed drastically as compared to the morality of the past, which was the basic cause for jealousy emergence. In fact, monogamous morality is on its last leg. Therefore, jealousy is also gradually coming to naught.