Matsya Purana — Solar–Lunar Motions
लोकसंव्यवहारार्थं भूतारम्भकृतेन च इच्छाद्वेषरताच्चैव मैथुनोपगमाच्च वै //
lokasaṃvyavahārārthaṃ bhūtārambhakṛtena ca icchādveṣaratāccaiva maithunopagamācca vai //
For the sake of worldly dealings, and because beings are set into activity, and also due to attachment to desire and aversion, and indeed due to the pursuit of sexual union.
This verse is not describing Pralaya directly; it explains the drivers of worldly life—social interaction and action—arising from the activation of beings and from desire, aversion, and sexual pursuit.
It frames the ethical problem a king or householder must govern: society runs on transactions and impulses, but dharma requires regulating icchā (craving), dveṣa (hostility), and maithuna (sexual conduct) so that social order (lokasaṃvyavahāra) remains stable and righteous.
No Vāstu or temple-building rule is stated here; the verse is psychological-ethical, pointing to desire/aversion and sexuality as forces that shape social behavior, which ritual discipline may aim to purify or restrain.