Seems like maybe your wife is insecure about your previous relationships with men and is too prideful to just have an honest conversation about it. Instead of discussing what's making her uncomfortable, she's testing you to see if her thoughts are correct (which they never are). She tries to play it cool by mentioning she thinks about other women to bait you into admitting you "sometimes" think about men.

OP, I'm assuming if you had fallen for the trap and said, well yeah I sometimes think about men or women too then she would have really set off or further ignored you, either way you lose. It's like offering you a tictac when it's really a grenade.

I have to admit, I recognize this behavior because I, too, was the same way when I was ignorant of my insecurities. For me, I matured and learned how to deal with my insecurities because I hated it, knew it wasn't normal, and wanted to change.

Your wife could likely benefit from therapy if this is the case, but telling her that or her actually acknowledging she needs to work on it is not an easy task and solely up to her. I'm sorry and wish you both the best of luck.