The 7th house is the house of marriage. Rahu is the planet of illusion, sudden strikes, and cruelty.
When Rahu sits in the 7th house, it creates a highly toxic environment for the spouse. Dr. Sharma uses a chilling phrase: "Aise nahi toh waise maara" (If not this way, then that way). This means Rahu will find *some* way to torture the life partner.
It could be through infidelity, financial ruin, constant mental harassment, or severe health issues. The spouse ("jeevansathi bechara") becomes the primary victim of Rahu's dark energy. Strict Lal Kitab remedies and absolute honesty are required to save the partner.