Mr. dB said:
'cause cars don't usually get rod knock on their own. I'm not suggesting that she didn't check her oil, I suspect that the oil pump died and the bottom end hasn't been properly lubricated for days, maybe weeks.
That, and I'm sure most of us have had the experience where we either drive the wife/girlfriend's car, or even just ride in it, notice something, and ask "So how long has it been doing that?" The answer: "Doing what?" Like it or not, sexist or not, some women have a knack for killing perfectly good cars.