The purpose of Śrīmad Bhāgavatam is to glorify the Supreme Absolute Truth, known as Śrī Kṛṣṇa, for the benefit of the suffering humanity. Śrī Vyāsa himself calls this Purāṇa the ripened fruit of the Vedic tree and compares it to the personification of rasa, or devotional relish. It is to be tasted by the rasikas, the connoisseurs of rasa, and relished by the sahṛdayas, the sober-hearted people or those whose hearts are imbued with sattva (SB 1.1.3)
Sex is union of the bodies. Material love is union of the minds. Spiritual love (Bhakti) is union of atmas. The later one can be inclusive of the previous ones.
