From John Frawley's The Horary Textbook, page 192:

In many relationship questions there is more than one 7th-house person involved: "I'm married, but do I have a future with my lover?" Always give Lord 7 to the person specifically asked about, which in this example is the lover. We can, if necessary, then find another planet to signify the other one. It is usually safe to take Saturn as significator of the unwanted spouse. If in doubt, the receptions will make the choice of the planet clear, or confirm that we have chosen correctly: ...

Following this rule in the chart in question we have Venus, Lady of the 1st and Saturn her husband, both in Cancer. They both "love" the Moon.

Frawley again:

Another significator which is often of the greatest importance is the dispositor of the Part of Marriage. If our main significators share a strong interest, as shown by reception, in a planet that has no role in the chart, four times out of five you will find this planet is the dispositor of the Part of Marriage.

While we cannot argue that the Moon has no other role in this chart, I think it is noteworthy that the Part of Marriage in this chart is at 3 Cancer, ruled by the Moon.

Tom

I hadn't thought of using the Part of Marriage. I'm going to insert it into my charts and see what happens. Good thinking!

Thank you all for your input and interpretations? My friend did at least try to move on and put this guy behind her. I will briefly update you as to what happened.

There is indeed a third person involved ? he has a girlfriend, who he lives and works with. This relationship had begun while my friend was seeing him on a casual basis and effectively ended his liaison with my friend.

Shortly after I posted here, my friend took the advice to move on and met someone else with whom she fell in love. However, for various reasons this did not last. My friend was very emotionally committed to the relationship, her new boyfriend less so. They broke up and my friend became quite depressed. She stopped going out and didn?t have a social life for quite some time. Then out of the blue in May this year, the first guy got in touch with her via text message. He basically said that he had been wanting to contact her since the last time they slept together (which was before he got together with the other girl), but didn?t have the nerve (his words). Their Mercurys are closely trine, and this began some very intense and sexual text messaging ? constantly back and forth for 12 hours a day or more, sometimes going on all night etc.

I could go into quite a lot of detail about the complicated history of the situation (going back 12 or 13 years to when they were both 17!) and the personalities of my friend and this man. Suffice to say that this guy asked my friend to have an actual affair with him, which she is now in the middle of. She doesn?t have much opportunity to see him, so he really is ?having his cake and eating it?. It is mainly played out through text messages with occasional physical meetings. I have advised my friend both from a personal and astrological point of view it is not a healthy situation, and I think she knows that deep down. But she still desperately wants to believe that he loves her and she believes their connection is fated. My friend is very attractive and seductive and frankly this guy is anything but. In my opinion (based on personal knowledge of him) he gets a sense of power from her that he doesn?t (and wouldn?t) get anywhere else. He craves that quite intensely, if nothing else. I also think that he is a little scared of her as she is very intense and impulsive and he likes his security, although he never seems to be satisfied with what he has and is constantly complaining that he is bored.

Just out of interest I did an event chart for the exact time of the first text message that this guy unexpectedly sent my friend and which re-ignited this situation. It is quite an interesting chart ? the moon is rising in the chart opposite his natal moon, and weirdly enough the AC is 9 Libra (the position of Jupiter conjunct Vindemiatrix on the AC of my original horary chart!).

I think this is a time bomb and inevitably sooner or later people are going to get hurt...

When you discuss using the Part of Marriage, I assume you are referring to the Part calculated from the horary and not the nateals of either the querent or quesited, is this correct?