People should love not for sexual pleasure - or any form of pleasure - but because they love each other. There are four kinds of love, corresponding with the four Ashramas and four paths of Yoga:
Love made by continual habit: the lover becomes accustomed to loving the beloved by ritualizing the act of love. As some people love to pass time in some way or another, or the rituals of a holiday, or become accustomed to a special place for dinner, certain foods and drinks, greeting the beloved upon their return in a certain manner, or by wearing a set of clothes, or accustomed to the rituals and habits of a home, a person may consciously devote themselves to their beloved and become accustomed to them through ritualized habit - and by sharing this ritualized love with their beloved accustom both beloveds to the ritualization of their shared love. The lovers perfect their love by loyalty and duty, as in a profound act of Bhakti Yoga or Vanaprastha practice. When perfected, this act of pleasure exceeds any physical pleasure from sex.
Love made by thought: the lover is not habituated, but is idealized through symbolism. As a Eunuch might still symbolically share his love by a kiss, or an embrace, the holding of hands, a smile, or some other gift or demonstration of the heart, so may anyone convey the thought of love to their beloved - even as, by Karma Yoga a Grihasthi may by action undertake profound sacrifice and dana. When perfected, this thoughtful pleasure exceeds any physical pleasure from sex.
Love made by belief: the love which is mutually perfected in lover and beloved by continence and self-control is very similar to the manifestation of wisdom through Jnana Yoga in Brahmacharya. Such a love is innocent and pure, each lover knows they are their beloved's, and sees no difference between their own identities. When perfected, this full-hearted pleasure exceeds any physical pleasure from sex.
Love made by perception of form: when the illusion of form is understood to be a manifestation of love itself, both lover and beloved share an exquisite love, superior to the pleasure of all other kinds of love: such a love exists only for its own sake. Like a Sannyasi practicing in profound Hatha Yoga, the lovers perfect the form, the nature of their love without regard to the consequences. Exceeding definitions of duty and loyalty, exceeding concepts of sacrifice and dana, exceeding even the ability of self-control and continence, the natural, uninhibited and wild state of such a love is itself an expression of Truth. When perfected, this spiritual pleasure exceeds any physical pleasure from sex.