The point of life from a purely secular and scientific perspective is for 2 things:
- Having lots of kids that will live long enough and be healthy enough to have their own kids.
By happiness I mean the two types short term (food and drugs) and long term (fulfillment passion meaning etc). These are measured in serotonin, dopamine, etc.
By having many kids I mean a lot of kids that will grow up old enough to have their own kids. I think that this can be seen in the research of evolutionary theorists. And the findings regarding our perceptions of beauty ( http://www.medicaldaily.com/men-perceive-thin-female-body-shape-physically-attractive-due-youth-and-fertility-350476), perspectives, way our bodies look and how life formed.
We balance these 2 life purposes of happiness and having lots of kids. It is why we work hard to try and attract a mate that is young, healthy and able to have a lot of healthy offspring who will grow up to be healthy enough to do the same. And it is also why we are always looking for ways to give us another high in short bursts or long term bursts. As if you really break it down and ask why a million times it all comes back to happiness and continuing life to the next generation.
Slutshaming, aversion to the “whore” and presentation of the “virgin” as well as monogamy, and other cultural taboos are made to ensure that the children will be able to live long enough to have their own kids. As appears to being children of single moms without support. It is also based on people who can’t get their own pretty healthy spouse and are therefore trying to even the odds (see what the people look like who are the most virulent in these ideas-usually not very good looking). Or based on society’s overall goal of creating an environment where its citizens children will be more likely to grow up and survive to the age to have their own children.