In Astrology, Mars represents sex and aggressiveness, while Saturn represents restriction, discipline, and control.
When there are hard aspects (conjunction, square, opposition) between Mars and Saturn in synastry, it seems that no matter what the Mars person does, the Saturn person is bothered. Nothing is ever “good enough” for Saturn. The Saturn person usually sees the Mars person as childish and irresponsible. The Mars person’s energy is the sort that makes the Saturn person very uncomfortable. More specifically, the Mars person’s self-confidence and assertiveness brings out Saturn’s insecurities, and in response, the Saturn person attempts to restrict and limit the Mars person’s actions by telling Mars what to do. Saturn may resort to constantly tearing the Mars person down through criticism and psychological abuse.
It is common for Mars to feel Saturn is condescending and treats Mars like a child. Mars may become angry with this and lash out at the Saturn person. The cycle of criticism and conflict can soon become a vicious cycle. This aspect lends itself to verbally abusive relationships, and can even escalate into physical aggression.
Since Mars is the planet of sex and physical energy, this aspect can also manifest into sexual problems for the couple. Saturn may find the sex disappointed, and Mars may sense this, and lose their sexual confidence. This is an aspect often found in the synastry charts of sexless marriages.
The harmonious aspects (trine, sextile), on the other hand, are much easier to handle. In this case, Saturn acts like a rock for the Mars person. The Saturn person is always there to support the Mars person, which Mars finds very comforting. Predictability and stability characterize the partnership. The Saturn person calms the Mars person down, while the Mars person introduces new ways of doing things to the Saturn person. Overall, this is a very positive aspect.