Do you think god really cares if you have sex before you're married?
Absolutely he does care. Fornication is an unholy rebellion against a holy God. Lust is also an unholy rebellion against a holy God.
You know it's wrong, because God's law has been written upon your heart.
Romans 2:14-15
14 For when Gentiles, who do not have the law, by nature do what the law requires, they are a law to themselves, even though they do not have the law. 15 They show that the work of the law is written on their hearts, while their conscience also bears witness, and their conflicting thoughts accuse or even excuse them
Romans 1:18-19
18 For the wrath of God is revealed from heaven against all ungodliness and unrighteousness of men, who by their unrighteousness suppress the truth. 19 For what can be known about God is plain to them, because God has shown it to them.
You suppress the truth in unrighteousness.
You ask the same kind of questions the Serpent asked in the Garden.
Genesis 3
Now the serpen
t was more crafty than any other beast of the field that the Lord God had made.
He said to the woman, “
Did God actually say, ‘You[a] shall not eat of any tree in the garden’?” 2 And the woman said to the serpent, “We may eat of the fruit of the trees in the garden, 3 but God said, ‘You shall not eat of the fruit of the tree that is in the midst of the garden, neither shall you touch it, lest you die.’” 4
But the serpent said to the woman, “You will not surely die.