Rahu in the fourth house gives extramarital physical relationship sometimes though, depending on other planets. In the fourth house, it may cause problems for/with the mother. It will decrease the quantum of Sukh(joy and pleasures) in life even if life is successful in all aspects. Rahu will never let the native be satisfied and content with what he has and will drive him to look for more always.
When Rahu is in 4rht house Ketu is in 10th. Ketu here may cause unusability in career and profession but 10th house Lord's position has to be checked.
There are so many aspects to study for chances of more than one marriage yoga.
If the 7th house is disturbed,
If the native is Manglik & Mangal MD yet to come,
If the lord of the 7th house is disturbed or in the vision of Mangal, Shani, or Rahu.
Sometimes, Brihaspati in the 7th house also creates such a situation as per principle 'Sthan hai karoti guru'.
Rahu in the 4th house decreases the happiness of life even after the native is rich. It decreases love from mother or there is a difference of opinion between mother & father-in-law.
For a detailed study go for Astrology reading by Best astrologer in Coimbatore Chandra Kundli is also important.
Sri Tulasi is a professional astrologer, life coach, and member of the Indian Astrologers Council. She has more than 15 years of practical experience in astrology. She is a regular columnist in many leading newspapers in India.
Visit her Website Spiritualsadhana