She left her husband and ran off with some young 'stud'.
retired racehorses being used as 'studs'
a horse that has been 'put out to stud'
(..) the nipple of my left breast. WOMAN: Two in my right nostril. One in my left eyebrow. One in my belly. One in my lip. One in my clit. And I wear a stud in my tongue. VINCENT: Excuse me. I was just curious, but, um... why would you wear a stud in your tongue? It's a sex thing. (..)1994 Pulp Fiction
(..) Oh, yeah. Oh, God damn. You are the best-looking girl I've had today. Oh. Yo, stud! Time's up, buddy. Coming in, ready or not. Hey, buddy, did you have yourself a good time? Whoa. (..)2003 Kill Bill: Vol. 1
(..) I bet Russian czars never paid that for a single horse. Khartoum. Khartoum. I'm not going to race him, though. I'm going to put him out to stud. Thanks, Tony. Let's get something to eat. Corleone is Johnny's godfather. To the Italian people that's a very sacred, close relationship. (..)1972 The Godfather