Trying to prevent humans from being human is the thing one should not do. You can make sure these things you talk about don't happen, but preventing human nature? That is wrong. Just because not everyone sees it the same way as you, having a single person to have sex with and only one, does not make everyone else wrong because the government is against that....
The number of ways it benefits you to be abstinent and then monogamous is large, a few samples:
1. No children before you are ready.
2. Near-guarantee you'll never have an STD.
3. Much less heartbreak.
4. No child support payments (if man), no being a single mother (if woman).
5. You are more likely to be middle class or higher.
6. Your children are less likely to be involved in crime.
7.
Your career will not be destroyed by sleeping with foreign spies.
The number of benefits to being promiscuous:
1. Pleasure.
That's it.
Human nature involves being horny, yes. That doesn't mean you should let it control you, even if it will always
influence you. I'm far from perfect at controlling my hormones, but I've managed to get into my thirties as a virgin, and while it hasn't been easy, it's had a lot of benefits. Including short-term poverty not being massively complicated by long-term financial burdens such as alimony or child-support.
I don't think we'll ever be at a point where
everybody is abstinent until marriage, or nobody ever cheats once they're married. But the more people who at least aim for that, the healthier and happier our society will be. I'm not advocating for government enforcing this morality either, but I certainly would like the government to stop
subsidizing promiscuity.