The Eighth House is an important house in relationship astrology because it represents areas of a relationship that are not easily visible on the surface, such as passion, intimacy, trust, and commitment. In relationship astrology, the Eighth House holds clues to the deep, hidden motivations of two partners, and how those motivations can result in either harmony or conflict. This house can also show how the two partners interact at a subconscious level, allowing one to gain insights into how the relationship works and how it can be improved.