Not every house is a home. Not every relationship is a marriage. They're qualitatively different things. Namely, a marriage is a relationship you are inclined to stay in, even when it isn't fun and easy. That is, after all, why people often don't want to marry. If they were identical things, the choice to marry or not would be completely random.

Marriage tends to correlate with higher fertility and increased familial responsibilities through an expanded extended family, and (for most wives) the burden of combining them with paid employment. That's why wives tend to look run-down: they have more responsibilities and work harder. They also (ironically) tend to earn higher salaries, provide more childcare, do more housework, and get less sleep, than never-married women, including single mothers. They are more-likely to be successful entrepreneurs and savers, and are more-likely to be actively involved in their communities.

The idea that being a wife carries no additional responsibilities, sacrifices, labours or stresses, denies the reality that young women can readily observe around them and denigrates the greater efforts wives are exerting. Which further contributes to their stress and makes the role even less appealing.

People used to understand that being a wife isn't just about having sex with some man that lives in the same house. It's a real vocation.