Incorrect. Come on now, there is research about this, so we don't have to guess or make things up. Men do have the instinct to have sex with many women, because those who had that instinct in the past spread their behavior genes more, yes. But there is also an instinct in men to stay with a woman and help raise children together. Those men who had this instinct gave their children a better start and therefore spread their behavior genes more. Especially in colder climates, where if you leave the children they will die. There, only those with an instinct to plan ahead, to be disciplined, to save food and to take care of their children would survive and have children who survived. As we can see, monogamy was always strong in northern Europe and in northern Asia. Whereas in Africa, the norm was often for a woman to raise her children by herself or together with a male relative with no family, usually an uncle or a brother.
Women, of course, have the Quality Before Quantity preference as a very strong behavior gene, because they can only have a few children, so sleeping around would be meaningless to them. Those women who sought the best possible mate for their few children had children of higher quality, and therefore passed on their behavior genes.
In the animal kingdom we see that the most advanced animals, like gorillas and elephants, stay with their children a longer time, while less advanced animals, like rabbits and rats, let the children go off on their own very quickly. The more advanced animals cannot wander off on their own right away, because their more complicated brains need a longer time to develop, whereas the brains in less advanced animals have simpler functions that are good to go much quicker. Humans being the most advanced animals of all, our offspring need the longest time with their parents, and the most attention and help from their parents. That is why humans have the strongest instinct to stay with their children. That is also why we have developed love, a chemical reaction that releases endorphines and a sense of identifying with someone else as if that person was a part of us. This improves our children's chances of growing up.
At the same time, men have that instinct to have many children with many women. The instincts are in conflict. But when there are many men around, a society works better with monogamy than with harems. In the Stone Age harems were the norm - the strongest men took all of the most desirable women. But monogamy gives all men a stake in developing a society, as that is best for their children. Monogamy was essential for developing and moving out of the Stone Age. Incidentally, the tribes we see in the rain forests who don't have any taboos against having sex with whoever, and who don't have close-knit families, and who, by the way, have no sense of private property either, are still Stone Age societies, always small and on the brink of starvation. Few men in that kind of tribe have an incentive to build something greater, as anything they build has to be shared with everyone else, including the moochers. And as they don't have any children who will pass on their name after they are gone, they see no point in building something lasting. So they just live for the day and nothing evolves.