Mars in certain houses creates difficulties for harmony in marriage and relationship. Some Vedic astrologers take these very seriously, others do not. Generally north Indian astrologers weigh them more heavily than those in the south.Such a placement shows potential conflict in relationship or a negative impact on the life of the spouse.
A person with such a planetary placement should generally only marry another person with a similar placement. A too strong Mars in the chart of a woman is particularly difficult for marriage from the Hindu point of view as it would make her dominate her husband and perhaps cause him ill health or even death in extreme cases.
Such placements should not be interpreted too simplistically since over one-third of charts have them to at least some degree. I consider Kuja Dosha but don't weigh it too heavily. It is more an issue if Mars is in first, seventh or eighth. Then the other partner should have some form of Kuja Dosha to be on the safe side.