Saturn aspects in synastry are notoriously difficult to handle. Saturn represents depression, restriction, fear of rejection, distancing, as well as commitment. Saturn aspects are certainly binding, but come with many problems. Here are some descriptions of how hard aspects (i.e. the conjunction, square and opposition) from one person's Saturn to another's Sun, Moon, Mercury, Venus and Mars manifest in synastry.
Saturn Trine Ascendant
This combination indicates mutual concern for serious cooperation in martial, legal or business affairs. You will implement these affairs effectively through mutual discussion and planning. The Ascendant person will be able to provide considerable energetic support for the serious goals of the Saturn person. The Saturn person can help the Ascendant person build greater confidence, maturity and organization. The acceptance of mutual responsibility in this position favors marriages and professional partnerships.