And part of that is biology again, ancient primitive territorial instinct kicks in if you think others are being selected for sex over you.
For example, some people are horrified that I'm OK with my 17-year-old daughter having sex.
WTF am I supposed to do? Lock her up? Fuck no! She's 17, she's SUPPOSED TO BE HAVING SEX. It's what young sexually mature people are designed to do. Me on the other hand? Haven't gotten laid since August, and I'm pretty much OK with that. My mind is occupied with other things, which is one of the rare perks of getting older.
No no no, you're supposed to be all weird and uncomfortable about it. You need to arbitrarily implement bizarre and draconian rules about the who/what/where/when of her social existence that will be completely ineffective at doing anything, except straining your relationship.
And then she can grow up with warped ideas about sex and relationships, and if she finally develops a comfortable mentality about her sexuality it won't be until she's in her 30s, if it happens at all. Then when she has kids of her own (especially daughters), she can reflexively impart all of that psychological malaise onto them once they're old enough to be having sex.
This is how we keep ourselves so well-adjusted as a nation.