The Hard Knot In The Heart by His Divine Grace A.C. Bhaktivedanta Swami Prabhupada
In the lowest stage of devotional life, one is not an unalloyed devotee. anyābhilāṣitā-śūnyaṁ jñāna-karmādyanāvṛtam (Śrī Caitanya-caritāmṛta, Madhya-līlā 19.167).
To be an unalloyed devotee, one must be freed from all material desires and untouched by fruitive activity and speculative knowledge. On the lower platform, one may sometimes be interested in philosophical speculation with a tinge of devotion. However, at that stage one is still interested in sense gratification and is contaminated by the modes of material nature. The influence of māyā is so strong that even a person advanced in knowledge forgets that he is Krishna’s eternal servant. Therefore he remains satisfied in his householder life, which is centered around sexual intercourse. Conceding to a life of sex, he agrees to suffer all kinds of material miseries. Due to ignorance, one is thus bound by the chain of material laws.
Sex serves as the natural attraction between man and woman, and when they are married, their relationship becomes more involved. Due to this entangling relationship between man and woman, there is a sense of illusion whereby one thinks, “This man is my husband,” or “This woman is my wife.” This is called hṛdaya-granthi, “the hard knot in the heart.” This knot is very difficult to undo, even though a man and woman separate either for the principles of varṇāśrama or simply to get a divorce. Whatever the case, the man always thinks of the woman, and the woman always thinks of the man. Thus a person becomes materially attached to family, property and children, although all of these are temporary. He unfortunately identifies with his property and wealth. Sometimes, even after renunciation, one becomes attached to a temple or to the few things that constitute the property of a sannyāsī, but such attachment is not as strong as family attachment. The attachment to family is cause of the strongest illusion. In the Satyasaṁhitā, it is stated:
viśeṣam ca vido viduḥ
Sometimes it is found among exalted personalities like Lord Brahma that the wife and children are not a cause of bondage. On the contrary, the wife actually helps further spiritual life and liberation. Nonetheless, most people are bound by the knots of the marital relationship, and consequently they forget their relationship with Krishna.
—Śrīmad-Bhāgavatam (BhāgavataPurāṇa) » Canto 5: The Creative Impetus » Chapter 5: Lord Rsabhadeva’s Teachings to His Sons » Verse: 7 and 8, Purport.