That's a great question.Is it still classed as adultery...if man / woman lusts after each other in the mind?
God wired us to be attracted to each other.
Otherwise we wouldn't procreate.
Where do you draw the line?
Actually, I think it helps to understand the ancient culture. Physical attraction crossed the line at greed to become lust.
Women in that day were seen as property. If a man wanted another man's wife, it was his property that the one lusting wanted.
King David had Uriah killed so he could take his wife.
So, the look of lust is not only the physical attraction but the scheming, or wish to take possession. Add to the harem.
/