Moon in 8th House synastry is very important for the study of business or family relationships where issues related to inheritance emerge (for example, in a divorce). If the Moon is stricken in the natal horoscope of the “lunar” personality or in the synastry itself, then these problems turn into litigation and bitter disagreements.
If Moon in 8th House synastry is positive, we can talk about the possibility of good business and partnership relations in such areas of activity as the restaurant business, real estate transactions, farming, services, etc. Business and financial projects developed in the course of relationships can be a smooth continuation of family projects of one or both parties. And it’s true that, for the “lunar” personality, the adoption and development of these projects is a much more difficult task than for the personality of the Eighth House who takes on the functions of an ideological or spiritual leader and main sponsor.
The “lunar” personality, in the meantime, provides emotional support and the formation of a reliable stronghold for future relationships. The emergence of mutual interest in the occult sciences and psychology occurs with the mutual stimulation of the emotional and spiritual factors of the relationship of these partners.
from F. Sakoyan, L. Ecker
Moon in 8th House Synastry Explained
Moon in 8th House synastry is an insidious aspect (the Moon is falling here). Both you and your partner will feel a vague threat, or at least a strong tension, emanating from some unclear place but at times materializing in very specific conflicts whose reason may be very far from the true cause.
In family relationships, the Moon in Eighth House synastry can be difficult to work through, especially if the female Moon falls into the Eighth House of her husband or child. Then caretaking will often cause strong tension and protest which can be expressed in different ways. But the general meaning of the protest boils down to something like this: “Your concern, instead of calming and relaxing me, causes too much trouble and anxiety and excites me.”
Nevertheless, the Moon in the 8th House synastry can add a lot of pleasant spices into an insipid life, especially if the Eighth House is not stricken. For example, sexual relations in such a couple can be accompanied by deep and mutually satisfactory meditations when the contact between the partners is felt stronger than in any other situation. But if something goes wrong, sex can become simply impossible.
In general, the Moon in the Eighth House synastry is an acutely intimate aspect, which at a low level can give rise to mutual energetic vampirism, psychological parasitism, and the ability to bring each other to perfection, depending on how you spin it. It will be difficult for you to protect yourself from the partner, but working this out the partner turns out to be capable of a subtle intuitive understanding of the most confusing circumstances of your inner life, and the two of you will be able to cooperate very subtly, especially when helping people who need it.
from A. Podvodny