In Vedic Astrology, when two planets sit in each other's houses (e.g., Mars in Moon's house and Moon in Mars's house), it creates a "Parivartan Yoga" (Exchange Yoga). This is generally considered highly auspicious, as the planets support each other like close friends.
But Lal Kitab gives a strict warning: The exchange of Jupiter (Guru) and Venus (Shukra) is disastrous.
Jupiter represents the native (the soul/husband), and Venus represents the wife. If they exchange houses, it means the husband and wife are physically together, but their destinies are pulling them in opposite directions. Eventually, one partner will be forced to relocate for work, or they will become emotionally distant.
As the old song goes: *"Kitne door... kitne paas."* (So far... yet so close).