Maybe saying "leftovers and best before" is harsh, and there's better ways to say it, but due to things like menopause and age related health problems, it's better to get married younger, especially if you want children.
Plus, science says that past 35, it gets harder for people of BOTH genders to get married. It is what it is, the way we evolved and bred as a species, aging gracefully wasn't selected for, only having kids fast before war, disease, famine, or hard labor killed you.
Our ancestors lived fast and died pretty, due to a lack of science, health care, and social stability. Historically, the long lifespans of today are an anomaly. Hence, why there's stuff like baldness that pops up later that wouldn't have been an issue throughout most of history, because you wouldn't live long enough to discover that it was actually a problem in your genetics.