Here are basic indications in a chart to infer that the native will face litigations in marriage / through spouse... Ofcourse those who know astrology will be able to understand these better : (These things may not hold 100 % true depending on other characteristics of the birth chart ....)
1. Heavy 6th house : 6th house is shatru sthana and represents the enemies of the native. Diseases are also beyond one's control and give lots of trouble, so diseases are also represented by the 6th house. If there are a lot of planets in 6th house, 6th house becomes heavy and the person becomes vulnerable to litigations / diseases.
2. Planets in 6th house :
---- If the lagna lord is in 6th, generally such a native is the biggest enemy of himself. He creates troublesome situations with friends and relatives.
__ If the 2nd lord is in 6th (2nd stands for family and accumulated wealth), the person has to lose a lot of money on litigation / diseases. He might suffer from chronic illness / litigation during dasha and antardashas of planets connected with the 6th house (lord of 6th as well as planets present in 6th). Since 2nd is also the house of family, the family of such a native suffers badly with him.
3. Placement of lord of 6th house : Lord of 6th when placed in 2nd can give a person a job related to hospitals or courts (lawyer / doctor) and the person might earn through litigations... But, 2nd is also the house of family, so, such a native, though earns from litigations, in the process loses his/ her family members (physically or emotionally) as 6th is a dushsthana and lord of 6th will spoil the house of family.
4. Last, but most important point : Lord of 7th (spouse) in 6th (litigation/enemity) house or conjunct the 6th house : - Litigation through spouse / enemity with spouse. In dashas and antardashas of 6th as well as 7th lord, the effects are realized to the full. 6th house (litigation/ enemity) is 12th(loss) from the 7th (loss of spouse), so it causes loss of spouse through litigation .....
Anybody having an opinion on this is free to discuss ....
BTW, those who do not believe in astro are free to hold their opinion but I would like you to know that I was also a complete novice, belonging to a family where no one ever cared for any astrology... but situations dragged me into astro and now I find this field amazingly true ..