This is a great question. I got it, in a round about way, from Lisa. First of all, Saturn is glue.Secondly, Saturn is parental. Thirdly, Saturn is discipline, maturity and reaching goals. Saturn is like all planets, in that they can be a blessing or a curse. The most common way to be a blessing is in a positive aspect, such as the trine or sextile. The most common way to be a curse is in the negative aspects of the square and opposition.
I, always, get hostile feedback when I use the terms negative and positive. I do think there are blessings and curses. The curses may, indeed, make us stronger. They may, indeed, lead us to God. However, they are very difficult and they are a challenge. Perhaps, I should use the word “challenging” instead of negative. I will give you that, but squares and oppositions do not allow for change. One must work around them.
Back to Saturn in synastry. Saturn in trine or sextile is a good kind of glue. It holds people together, but does not feel like a prison. Saturn in hard aspect may hold people together, but it may feel like a prison. With Saturn, the conjunction is a hard aspect.
NOW, the big question is “Can a Saturn conjunction be good?” The answer is yes, given certain conditions. The conditions are that there is enough love and simpatico to overcome the strict parent quality that the Saturn brings to the planet( or angle person). The angles are the Ascendant, Descendant, IC and MC.
I just met a lovely girl whose boyfriend’s Saturn conjuncts her Sun, exact. She likes the parental traits he brings to her. She likes someone to help her discipline herself because she finds it difficult to do, on her own. Hence, a Saturn conjunction works for them. However, they, also, have many loving and deeply bonding aspects, such as Moon conjunct Moon. Without these, Saturn in conjunction would, likely, feel like an unwanted bondage.