We’ve seen that many of the “Ten Commandments” are not necessarily what people think they are before studying the mitzvos. The idea of “Thou shalt not covet” is about as misunderstood as they come. To covet is to really, really want something. How can one legislate against a person really, really wanting something?
For practical purposes, one does not violate the prohibition against coveting until one takes some action to deprive the rightful owner of the item in question. This is true even if the object changes hands legally if it’s done under duress.
Here’s an example of coveting gone wrong in the extreme: In I Kings 21, King Ahab desired the vineyard of Naboth, who wouldn’t sell. Ahab’s wife Jezebel fabricated charges of treason against Naboth so that he would be executed and Ahab would acquire the property. Coveting may not always end in murder, but any scheme to acquire another’s possessions against their will is a violation of this mitzvah. Whether it’s a movie where a handlebar-mustached villain plots to steal the farm or a TV sitcom where someone tries to steal another character’s girlfriend, it’s the attempt that violates the mitzvah.
In a more spiritual, self-improvement sense, the ibn Ezra in his commentary says that certain things are simply ridiculous for a person to desire. The average person is never going to marry a princess; it’s just not realistic. For that matter, a person is never going to marry his own mother – there’s kind of a huge taboo against that! (These are the ibn Ezra’s examples, not mine.) Just like a person puts these ideas out of his head, he should recognize that what God has given another person is equally out of bounds. A person must train himself to be happy with his lot in life and to see others’ possessions as so taboo that the thought of pursuing them would seem ludicrous.
The prohibition against coveting is #265 of the 365 negative mitzvos in the Rambam’s Sefer HaMitzvos and #40 of the 194 negative mitzvos that can be fulfilled today in the Chofetz Chaim’s Sefer HaMitzvos HaKatzar. In the Talmud, it is discussed in Baba Metziah on the bottom of 5b. In the Shulchan Aruch, it is found in Choshen Mishpat 359. This prohibition applies to both men and women, in all times and places.