A fixed dollar band defines ‘similar’
The Census comparison classifies annual earnings within $5,000 as similar. That is a transparent rule, but the same $5,000 represents a different proportion at low and high income levels.
The result uses individual annual earnings, not household income, wealth, hourly wages, or control of family finances.
Children in the household mark a large difference
Among opposite-sex couples without children in the household, 36% had partners whose earnings were within $5,000. Among couples with at least one child, the share was under 10%.
That comparison is descriptive. It cannot by itself separate childbirth, caregiving, age, occupation, work hours, selection into parenthood, or other explanations.
Income preferences are not the same as couple outcomes
These records show earnings after couples formed and lived together. They do not reveal minimum-income standards people used while dating.
For a dating pool, personal income can estimate how many people meet a threshold. For a relationship article, paired earnings show how established couples are arranged. Combining the two would confuse preference with outcome.