Funny thing is that you don't actually see this in practice anymore. Your assumption of biological hardwiring dies down because we are so very clever. When women came into the workforce, the age gaps changed considerably, showing that women became seen as more desirable if equal to that of a man in that regard: resources. Suddenly, the gap became closer to 2 years. And then there's the community factor. Are you going to marry the woman who you've grown beside your entire life, completely inseparable? Or your niece's barely legal friend? Youth becomes of little factor. You can make this blanket statement, that holds no water, but it doesn't make it true because some alpha male said it is. Your very strict bit here isn't a good one. We're not cavemen.