Mars or Kuja Dosha, which is commonly known as Mangalik in india is considered as prime cause for problems arising in married life, late marriages, divorce, second marriage, legal issues related to family etc.
In general, the below 11 rules are defining Mars dosha in a chart cast as per KP(krishnmurthi paddathi) principles.
Legend : CSL (Cusp SubLord), sub(subdivision in k.p)
1. Mars in own star or in Sun star, and occupying any of 1, 2, 4, 7, 8, or 12
2.Any planet deposited in the Star or Sub of Mars, and occupying
1, 2, 4, 7, 8, or 12
3. 7th CSL is Mars and is located in 6, 10 or 12
4. 7th CSL is in the star of Mars and is located in 6, 10 or 12
5. 7th CSL is in the sub of Mars and is located in 6, 10 or 12
6. 7th CSL is Sat and is located in 6, 10 or 12
7. 7th CSL is in the star of Sat and is located in 6, 10 or 12
8. 7th CSL is in the sub of Sat and is located in 6, 10 or 12
9. Mars is the 7th CSL and is located in 1, 2, 4, 7, 8, or 12
10. Mars is the starlord of the sublord of 7th cusp and is located in
1, 2, 4, 7, 8, or 12
11. Mars is the sublord of the sublord of 7th cusp and is located in
1, 2, 4, 7, 8, or 12
In many cases irrespective of the lagna , mars if satisfying any of the above 11 rules is known to cause troubles regarding marriage.
But if venus is well placed in a chart, married life will be good even though mars may have delayed it.
So, in male horoscope Venus and in female horoscope Mars will have to be in favourable position to overrule the mangalik or kuja dosha effects