Wow you can imagine a woman being jealous in real life? Crazy man, that's never happened.
"A distinct impossibility, never has there been such thing."
No kidding though, a friend's sister got pregnant and she 180'd her position on kids after having a niece (now she wants one). While it can seem petty and silly at times (actually, it can be lethal if they decide to poison someone over it or kill themselves if we go off of the more epic feminine jealousy narratives), it's really a useful evolutionary social trait. Of course, like all traits, it's best if one can control the worst excesses.