SYNASTRY-SATURN SQUARE OR OPPOSITION MOON

If there are other aspects to the moon by the more romantic planets ie. Neptune, Venus, or Jupiter this will soften the Saturn effect and in some cases negate it entirely. Otherwise, this makes for an emotionally serious interaction and difficulty or resistance in the emotional expression for the couple. More often than not, (with this aspect) one or both parties may withhold their emotional feelings, hide or censor them when with each other and for each other. 

There is usually some form of emotional blockage. This can take form in some cases as  one or both parties might actually want to take the relationship to the next level if you are dating, one or both of you fear rejection. 

Other times, it's a serious tone that takes place you only feel comfortable with superficial talk and might be unable to relax and enjoy the other's company being open with one another.

There is an awkwardness to expressing emotion, sensitivity or even romantic or emotional concern. 

 This can be boggling, to both people involved. On one hand, emotional trust is an issue, along with fear, and on the other, there is something about your interaction together that just doesn't allow feelings and expression to run freely, an invisible wall exists.

However, there is a great deal of security, reliability and dependability that goes with this placement because you both desire one another but fear each other just the same. Or one of you finds the other too emotionally needy, or expressive and the other does not feel comfortable. 

However, because you both wish you could express how you feel you both are likely to show it in other ways. These ways are usually not very obvious but if you look closely, the terms of affection are quite endearing and in economical ways, or by doing things for one another. 

 One partner usually the Saturn partner is the one with the difficulty and the moon person is looking to Saturn for the validation. 

Lack of Saturns response can cause the moon person to feel closed off, rejected and lonely. The Saturn person is often seen reacting defensively and even callously to their partners desire for affection.

Saturn is restrictions and he puts up emotional blockages when in aspect to the moon. It is not that the Saturn person does not want the moon, there is something in your interaction together that is emotionally stifling. This is more so, if either person has Saturn hard applying aspects in their natal chart.

 Unless both parties are consciously aware of this and each makes a conscious effort to communicate regardless of the fear. Saturns relationships usually take years to consummate if they ever do. Simply because of the on and off and the inability to truly emotionally connect. Saturn can be cold and hard, and may offend the Moon, making them feel unwanted. This is Saturns way of testing the love of the Moon.
In some cases, Saturn want's to know how you handle rejection, and if you are independent enough to live without him, in others he is simply unable to express love the way that the Moon person desires. 
Saturn has strange ways of doing things and it's not for everyone. If you are not one that likes to chase, or can handle an emotionally cool relationship, this aspect will drive you mad. 
Saturn will push you to run, but if you stick it out and show that you're a grown up, and don't mind, being rejected, or being in a relationship where there are emotionally blockages, and a certain coolness, this can work for you. 
These blockers are based on the insecurity of what the other may feel and is usually produced because of a lack communication when it comes to how one feels about the other. 
When the Moon person makes an attempt to show affection the Saturn person may push the person away in disbelief or doubt. The Moon person can feel hurt and close down to protect him or herself. 
This can be a cycle that is hard to break if one or the other makes no attempt to open up. If there are other friendly aspects to the moon, then this can just add a seriousness to it, or perhaps the issues will be outside forces like other's getting in the way, recently divorced, not emotionally available or maybe just issues around food, or the Mother. 
However, in synastry the Moon is how you express yourself emotionally and what you need emotionally and with Saturn in a difficult aspect you are not likely to achieve either one very easily. 
Saturn has been known to bind two people together for best or worse and I think it has to do with the fact that two people love each other but are not able to emotionally express it, so the relationship lingers on, in hopes that they will one day get what they want. Saturn has the upper hand because he plays hardball, and keeps the distance entrancing his partners in the quest for their love and affection.