I liked this article:

Sexual Desires

“Why did God give us sexual desire if it's a bad thing? Even if you only lust over your spouse, you would most likely have felt lust for them before you married. After all, lust plays a big part in our choice of marriage partner. So why did God set us up to fail?”

You seem to be confusing lust and sexual desire. God did give us sexual desire and it’s not a bad thing. In fact it’s a good thing. How else would we be attracted to a prospective spouse, and why would we even procreate if there was no “desire”?

So, what then is the difference between sexual attraction and lust? One dictionary says that “lust” is “uncontrolled or illicit sexual desire or appetite; lecherousness.” Or to put it another way, lust is pornography of the mind.

How then do we know the difference between "looking" and lusting? The answer is to listen to your God-given conscience. It will tell you . . . if you have a mind to listen. There's nothing wrong with simply seeing someone and having the automatic thought that she's attractive. But that's different from then formulating sexual thoughts about that person to lust for her. In case you're having trouble hearing from your conscience, here's another clue to help you: How would you feel if your spouse were doing that behavior? Would you mind it if she was entertaining lustful thoughts for other men, having sexual fantasies about someone other than you? We often have a hard time seeing wrong behavior in ourselves, but have no trouble seeing it in others.

Read the whole article here.