Csdrhrt

I envisioned a world where people are not bounded by marriage and females are free to choose those who they deem "accomplished" and have offspring with him.

The males "occasionally" interact with the young and "educate" them to be better than the others, therefore make sure their genes are passed onward, much like lions or monkeys in our world act.

The only problem is my race is "highly intelligent" and have a strong sense of "moral".

And here comes the REAL problem:

The "less accomplished males" will definitely grow jealous and envious!

NOBODY will accept the fate that he is inferior than the others and just die, ESPECIALLY when he is "intelligent"!

And the long period of "lacking female companion" (plus jealousy and envy) will definitely twist your mind and commit unspeakable crimes such as rape or murder.

And that is "most of the society"!

So if this kind of system was practiced for too long, bad things are bound to happen!

So is there any ways to prevent this sort of things from happening!? In other words how does this society "keep everybody happy"!?

Basically, lions and monkeys survive because the males are to "prove themselves" by surviving the wild on their own, whereas females are sheltered by the group which makes survival for them much easier and tips the scales in favour of females meaning that there are more adult females and they work together as a group.

When you have a more "intelligent" society by which I suppose you mean also a technologically more advanced society, you will have to change the way in which the males have to prove themselves to the females.
Two possible options of roles for your males are reasonable:

1. "the protector of society". Basically, being a good, reliable and trustworthy bodyguard, soldier, police man etc. earns you the right to be chosen by the females. This will not happen in your first years, but as an accomplished officer of 30+ years you will become eligible by females pretty much like in a dating service. In this way the physical fitness of offspring is guaranteed and these males are also all part of a strict moral code of "keeping to the laws" and always keep in training to still be able to perform in their jobs. In addition, they have a strong personal interest to do their jobs well, as they protect their own and the other children and women in the society.




2. "the scholar". Those are the intellectual upkeepers of society, scholars, scientists, engineers who will also have to invest years into their education and intellectual training. Again they will have to raise through the ranks of the "scientific community", making only the ones who have finished their PhD, published a certain amount of papers or research to find a certain number of patents eligible for producing offspring. Here, the genes of the most highly intelligent are to be passed on for the better of the society. While not the ones to protect their own and others offspring and no ideal for physical fitness, they will be the ones to educate their own and others' elected children and guide them to intellectual understanding under their tutelage.

In this way, the females can choose between an intellectual or a muscle man as their respective partners to foster the physical and intellectual fitness of their whole community.

When a female gives birth, most of the newbornes are females. The general makeup of your society could be 10-20% male and the rest female. This would encourage more females to get together with less accomplished, because the top 5% are already with a certain amount of females.

To pronounce this, you could etablish a social maximum of wives/partners a male can have, either due to social or biological reasons.

You don't explicitly say, but I'm going to assume that you want a human society. Some of this becomes easier in an alien society, as we don't have to work around actual human behavior.

NOBODY will accept the fate that he is inferior than the others and just die, ESPECIALLY when he is "intelligent"!

Sure, so the society won't operate that way.

Instead, there will be a constant proffer of hope that some day, the currently inferior will prove himself and gain a mate. By the time that he realizes that he never will prove himself, he is over the hill.

The initial claim will be that they are too young. And some will graduate from that to become head of a pride. But others will be just a bit weaker or slower. They will always be behind the best of their age. Some might be enough smarter or have the ability to learn to be better such that they can compete later in life.

Such a society might have a competition culture, where most lose but all think that they can win. Perhaps the competition is kept always close. So even the weakest and dumbest think that they are just a step away. Individuals may spend large parts of the year training for the competitions.

The females in a pride may support one candidate over the others and give preferential treatment, adding a political component to the contests.

And the long period of "lacking female companion" (plus jealousy and envy) will definitely twist your mind and commit unspeakable crimes such as rape or murder.

Well, the lion solution is that if you murder one of the lucky few, you become one of the lucky few. I.e. a male leader of a pride may lose a challenge to a nomadic male, who then becomes the leader of the pride. That might last a long time in a society like this.

Rape is more complicated. Lions have an estrous period where they strongly want to mate and do not have sex outside it. It is unclear if they would ever consider themselves to have been raped. I.e. rape may not be a meaningful term to an estrous species. Sex is more like scratching an itch than an activity pleasurable in its own right. Humans of course work differently.

Note that male lions are greatly outnumbered by female lions in a pride. With humans, the females might gang up together and kill an abusive male. It's unclear what would be considered normal in such a society and what would be considered over the line. But a male attacking a lone female would be rare, as females travel in prides. It's only the males that travel alone or in small groups.

It is also possible that this society would have more bisexual members. Young males might band together for companionship and sex. Later, they might "graduate" from that to a pride. Some may prefer the companionship of other men throughout. This may be described as a spectrum of sexuality, ranging from only mates with females to only mates with males. Same sex sexual activity has precedent both in humans and in lions.

An individual male who is sexually aggressive, only interested in females, and unable to find a pride might be subject to destruction or imprisonment. Or simply may be barred from the competitive events that allow one to find a pride after breaking the rules in some way.

Males may also sublimate their sexual desire in other activities. Or masturbate.

One reason that people would join the Catholic church was so as to remove the threat to their relatives. Because priests and monks do not marry, they can't have (legitimate) kids. So they are not a threat to their siblings' dynastic hopes. This made the church a useful place to send younger noble children. They would find alternative ways to compete, possibly advising their brothers or nephews. Or they might compete in knowledge. When those with knowledge but not muscle would be allowed to reproduce would be a major step toward civilization in that society.

The first step might be a particularly strong male giving his castoffs to his brother. If someone tried to challenge the weaker brother, perhaps the stronger would fight his challenge for him.

Another option is castration. Perhaps anyone can challenge, but if the challenge fails, the challenger is castrated. This could be brought forward around the same time that the knowledgeable started being allowed prides. Prior to that, the loser might always be killed. In that circumstance, castration might be the more merciful alternative. But as civilization develops, it will become the primitive remnant, as some see capital punishment and imprisonment now.

Both death and castration make challenges risky. So rather than challenging constantly in the hope that you might get lucky, you prepare for one single challenge. But the hope remains.

This allows for competitions based in something other than physical combat that still have serious consequences. Yet another alternative would be to simply give each and every male one chance at a challenge.