A warning sign but not a rulebook
Vedic astrological science believes that our lives are governed by the planetary influences. But astrology and especially marital astrology should not be treated as a rulebook. On the contrary, it should be treated as a book of warnings from which you learn about general possibilities and guide your life and its decisions accordingly. Generalising extramarital affairs based on astrology or blaming infidelity on the planetary combination is neither right nor justified.

You can have a troubled marriage for various other reasons. There are many other reasons people have extramarital affairs, like lack of time, boredom, lack of emotional and physical support, intimacy and lust. Astrology can maybe give you warning signs based on planets, but if you experience that situation, rather than just blaming planets, you should pateintly try to navigate through crisis, to find solutions for it. Even if the solution may lead to separation.
While reason of extramarital affairs can be different for different people, planets that control the sexual urge of people play an important role. Some zodiac signs have more sexual urges and they tend to crave for satisfaction outside marriage. Let’s have a look at the planets and houses that are said to play an important role in predicting extramarital affairs. Certain planetary combinations indicate the possibility of extramarital affairs in astrology.
If your prospective groom or bride’s Moon is in trine to Mercury, it could indicate chances of infidelity. Another planet to look for is Venus. It also has a significant role to play in extramarital affairs and astrology
Mars and Venus conjunction in Scorpio sun sign in the 9th house is a potent indication of extramarital affairs. Mercury and Moon conjunction in Gemini is also an astrological indicator of infidelity in both men and women
If Moon is conjunct with Mars, it can lead to clouding of the mind, and a person can become inclined towards illicit relationships. They are more prone to cheating on their partners with extramarital relationships
A badly afflicted Moon and Sun in the fourth house can also indicate the person’s tendency towards having secrets. They can also have illicit relationships with older or aged women.
Moon conjunct with Venus gives rise to extreme and sensuous thoughts in the mind of the native, which can hint at tendencies towards extramarital relationships
A person may be inclined to have an extramarital relationship if the Moon in his or her kundali is conjunct with Rahu. This combination makes one’s mind clouded and prevents rational decisions

Stars do give signs about your partners
Venus is the planet of love and romance. Venus, when conjunct with Rahu or Mars, boosts passion and lust in one’s life. And this conjunction in signs like Scorpio, Aries, Libra and Gemini can increase the chances of an extramarital affair
Moon and Mercury, in conjunction with the sun sign Gemini (the sign of love and romance) also indicate a strong possibility of adultery. The person may also get exposed for his extramarital affair if the combination is aspected by the planet Saturn
Vedic astrology also believes that before marriage the horoscopes should be checked for Punarbhu Dosha – which is basically the conjunction of Moon and Saturn. This combination is believed to make a partner cheat and create a lot of havoc in unrest in a marriage
Certain horoscopes also have some effect on inclination for extramarital relationships. Linda Goodman’s Sun Signs book claims that Capricorn men are prone to straying later on in their lives. Scorpio men and women are also prone to being lusty and getting into extramarital affairs
11th House: The house of desires and extramarital affairs
11th house is also known as the house of profit and desires. It is called the house of excess. It means that it will multply traits of plates placed in this house. If there is Jupiter in this house, it will bring abundance of wealth, sometimes more than one can digest. Venus in 11th house indicates extramarital affairs. It shows abundance of wives (one at a time) or affairs. This house is one of the carnal desire trine (kaam trikona).

To strengthen a marriage, spread some kumkum where your husband sleeps, and in the morning apply the same in the partition of your hair chanting the name of Maa Parvati
Lighting a tablet of camphor in the bedroom every night may also rid you of your partner’s secret love affair
If you know the name of the person your partner is having an affair with, writing it on lotus seeds or makhana and burning them till ashes are formed may also work as a remedy for extramarital affairs