The problem that astrologers and general populace is that they view Saturn as malefic planet for all cases. It is true that Saturn is a malefic (क्रूर ग्रह), but is not a malefic for all horoscopes and all lagnas. It is a natural malefic and causes scarcity and delay. However, it is not a functional malefic in every janma kundali. Therefore, Saturn’s effect on various rashis and janma kundalis needs to be studied carefully. Please refer to this article on Saturn in order to understand the treatment of Saturn in the Vedic horoscope. Further, transit effect of Saturn through Scorpio from Nov 2014 through Oct 2017 is described in this article, where it brings auspicious results for few signs. Its inauspicious results are also muted down bringing mixed results for some rashis. Please refer to the article for details.
A strong Saturn is responsible for a stern, discipline and uncompromising state of mind. Effect of such a strong Saturn is important for stability in marriage or in any other institution. So, in a way, a strong and well placed Saturn’s affect will aid in not only causing marriage but in maintaining it as well. Saturn transit over natal Saturn or aspecting the houses will cause marriage. Venus, the karaka of marriage in a male horoscope is a friend of Saturn. Venus conjoined with Saturn in kendras of main rashi kundali and navamsha chart with other beneficial aspects is good for Venus and by implication good for relationships.
Weak Saturn causes mental worries and agony that either delays marriage or causes rift between husband and wife after marriage. Saturn by itself will not do much harm. Problems do not aggravate unless other malefic planets join. Saturn located in 7th house, further aspected by malefics, will cause delay in marriage or will indicate lack of marriage in the horoscope. Rahu and Mars cause bigger damage. Mars causes Manglik Dosha, resulting in both delays and break in marriage. Lord of 6th and 8th houses are even more important than Rahu and Mars. If 6th and 8th houses are occupied by rank malefics at the same time, it can deny marriage or at least not allow marriage to happen in their dasha/bhukti.
Mars as a fiery planet in a janma kundali either affects the emotions or causes commitment related problems in the individual. On the other hand, Rahu is putrakaraka and will confer marriage, but rather unusual one and brings in some eccentricity in marriage.
To predict problems in marriage, position of 7th house lord in the horoscope is more important than aspect of affect of Saturn. If the lord is located in 6th or 8th house, or if 6th/8th lords in a horoscope are located in 7th house, then there is a bigger problem.
I had read this tenet long time back either in Express Star Teller or in The Astrological Magazine and had made a note of it. I do not remember it now in order to give due credit to the author. It was written – स्थान वृद्धि करोति मंदः – meaning Saturn helps improve the karaka of the house that it is located in. Therefore, if Saturn is located in 7th house and is well placed, then it does not harm marital relationships and in fact helps sustain it. Aspects are more important – 3rd house sextile aspect and the 10th house back square aspect are more malefic in nature than the location itself.