NOTE. According to the rules of Dharma-śāstra, a married man can unite with his chaste wife during her fertile season to have children. But he who dislikes his chaste wife and therefore refuses to unite with her [when she is desirous of having noble children] accrues sinful reactions. This is indicated by Śrīla Śrīdhara Svāmī in his commentary to Śrīmad-Bhāgavatam 11.5.11.

In their commentary to this verse of the Bhāgavatam, Śrīla Prabhupāda’s disciples explain:

There is a Vedic injunction that in the proper season a husband must approach his wife at night at least five days after her menstrual period, if the wife has properly bathed and cleansed herself. Thus, a responsible householder should engage in religious sex life.

The injunction that one must approach his wife for sex life is explained by the Vaiṣṇava ācāryas as follows. Within the material world almost every man is very lusty and desires passionate sex life with every attractive woman he meets, or with any woman at all. Actually, for an ordinary materialistic man it is an accomplishment if he can restrict himself to relationships with his lawfully wedded wife. But because familiarity breeds contempt, the natural tendency is for the husband to gradually become envious or resentful of the wife and desire illicit connections with other women. Such a mentality is most sinful and abominable, and the Vedic scripture therefore orders that one must approach his actual wife, with a desire to beget children, and thus curtail the tendency toward illicit sexual connection with other women. Were there no such Vedic injunction ordering one to approach his wife, many men would naturally be inclined to neglect their wives and pollute other women by illicit connection.

However, such an injunction for conditioned souls does not apply to great souls who are fixed on the spiritual platform.