For those looking to the "why" of social norms as it relates to sexuality, there is a ton of fascinating research into why religion seeks to pair bond men and women at certain points in their lives...why society seeks to reward the building of families (stability, growth of the nation, focus on future planning), and why societies fail when they lose that foundational family structure.
Effectively, it's bad for society if the people in that society are too selfish...but it is good for them to have enlightened self interest towards their own family/clan/tribe.
At the micro level, this translates to raising children to become productive human beings with skin in the game...not feral humans with nothing to lose. Family, marriage, land ownership...these are critical factors. They give you something to love and something that you don't want to lose. Thus, stability.
This is also why sexual promiscuity was historically punished harshly...you risked all of those things.
In the modern context, you see this via divorce rape albeit in a one sided context in most cases.
At the micro micro level, you see risk in the form of partner count as studies show Oxycontin based pair bonding ability is decreased in women with direct correlation to partner count. Likewise, statistics on successful marriage are directly proportional to partner count, above a certain #. The surmised result is that you have a better chance at a successful marriage if you marry relatively young, to someone with a low partner count, who has a religious background that promotes children, home making, and family along with the exterior family structure (mother, father, grandparents) to support and reinforce that structure.
That's big picture...so there will be scores of people who show up to tell the world how they are the exception to the norm. Such is life.
Google oxytocin based pair bonding and marriage / divorce sexual partner count for further.
[This message edited by Unbroken78 at 5:51 PM, May 16th (Thursday)]