What's the point of burying only one person in a cemetery?

Also known as ghost marriage, it is to find a spouse for the deceased. Some boys and girls died for some reason after they got engaged, but they didn't wait until they got married. At that time, the old people thought that if they didn't get married for them, their ghosts would do mischief and make the family uneasy. So we must hold a wedding for them, and finally bury them together, become husband and wife, and be buried with their bones. In case there are solitary graves in the fields of men and women. Other boys and girls died before they got engaged. Out of love and yearning for their children, the old people think that they failed to choose a spouse for them before their death and should marry them after their death to fulfill their responsibilities as parents. In fact, this is where people feel. In addition, in the old society, people generally believed in the so-called "geomantic omen" in cemeteries, believing that the appearance of orphan tombs would affect the prosperity of future generations of family houses. At that time, some "Mr. Feng Shui" (called "Feng Shui" in ancient times) strongly encouraged this kind of yin marriage in order to earn more money. Vaginal marriage mostly occurs in aristocratic or rich families, and poor families will never engage in such activities.