Saturn harsh contacts are exactly that, "harsh". Ouch! Similar to the brick wall, it hurts when you run into it.
Saturn in synastry puts walls up and typically the Saturn person judges the relationship based on certain criteria which are usually very difficult to meet.
However, there are other aspects that can help soften Saturn's toughness, but when in hard aspect to Venus in love, there are not many. This is especially true if the Saturn person also has hard aspects in their individual natal chart to there Venus.
In this case, the Saturn person will have strong opinions on right or wrong behavior, and will often put their partner through many tests and trials that will require patience if the relationship is to progress. Saturn in Astrology always suppresses the natural expression of any planet it touches.
Saturn in synastry is a restrained energy, a block, sometimes from high expectations in a lot of cases insecurity and very commonly both.
Typically the Saturn person will act like a wet blanket to whatever planet it touches. If someone's Saturn is on your Sun, then you may feel you need to censor your natural expression of self, you may feel suppressed, insecure or judged around the Saturn person. There is often a pressure to behave accordingly, and you will find yourself paying more attention to what you outwardly express.
The Saturn person may unconsciously or consciously turn a critical eye on any fault you have or even put a damper on your happiness or excitement, most true when involving the Sun.
Saturn is somber, but even so there is much to learn from him in most cases. He makes us grow up and pushes us to be independent and to have expectations of ourselves and others.While (Neptune) allows us to look past these things, even brush them under the rug or imagine it's not so. And Pluto, will pull out our carnal instincts or make us think we have control over things, but Saturn always comes around, to show us that self-control, discipline, and hard work is really the only way because it's lasting.
However, Saturn's seriousness can take the fun out of life, and the relationship. High expectations in love but a lack of the giving energy in return and you can feel like your on trial, or blocked and in the negative it can prevent a relationship from the romantic bliss that many desire.
If a person's Saturn is square or opposite one of your personal planets, that planet will feel suppressed. The planet person can feel secure with the Saturn person but do not expect this is a passionate love relationship. Unless there are other strong Mars-Pluto or Venus-Pluto aspects, it likely won't.
Saturn loves hard work, and responsibility so you won't be sneaking anything by him the easy way. You will have to work for it.
For an even deeper analysis of Saturn in Relationships, you can continue reading more in the Private Members Only Section.