Saying it's unfair is as senseless as complaining about gravity.
Man's base desire is to take anything he wants, but we have to curb our desires. That's why we are above the animals. That's what the Matthew verse means.
“Enter through the narrow gate. The gate is wide and the road is wide that leads to hell, and many people enter through that gate. But the gate is small and the road is narrow that leads to true life. Only a few people find that road. - Matthew 7: 13-14.
But see, that's how it works. Man has a sinful nature and has to work to overcome it.
No, man has a natural desire to copulate that God gave him. You say "nature". By your own beliefs - that is just another word for "God given".
Man's base desire is to take anything he wants, but we have to curb our desires.
It is not that simple. Through brain scans, and our ability to see brain activity "live" - has proven that a males brain literally goes half dark when he is fully aroused. It is scientifically proven that a man loses his ability to think clearly and objectively. Specifically, his frontal lobe goes completely dark. This area of your brain is responsible for critical thinking. In other words - clouding his ability to process right and wrong and especially the results of his choices.
Don't you think that is a bit unfair???
God literally shuts off the part of our brain that gives us the ability you mention - why???
How fucked up is that?
This is why some belief systems, like the Gnostics, believe that God the creator, and God the Savior are two different beings. That a lesser God created man in his own likeness that was not pure like the true God.
The true God, seeing what the lesser God did, took over and gave man grace and repentance.
Some other heavenly beings, such as the devil, were totally against giving humans grace. And the devil set out to prove man's unworthiness against the true God's wishes. And so God banished him.
In a nutshell, the legalistic Bible-only based belief systems are deeply flawed, and go against common sense. Why on earth would such a loving, intelligent creature create man only to make it almost completely impossible for him to be good?