Is it okay for a married woman to flirt?

Only a few weeks ago, Carol had a problem with her boss who is a sex predator and she reported her to the HR and the boss has not stepped on her line ever since.
Now, you have a problem. Mid-week, Carol used her WhatsApp on your laptop since her phone screen cracked and she is yet to replace it or buy another phone. And then she forgot to log out. And like a curious cat, you decided to go through her chats.

Damn, so many guys out here who thirst after married women. You went through her chats and there were a dozen men showering her with praises, praising everything from her flawless skin, to her bottom, to her dimples and everything desirable she has.
To some, she is courteous, occasionally blushing. To some, she is downright rude, like there is a hapless chap who has been fed blue ticks, he must be overweight from that diet.
To some, she is unusually playful and downright flirtatious. In all of them, nothing alarming, except for some dude called Tom.
Tom is the mysterious man in your wife’s phone book. You can’t dare ask her who he is. But every time you have handled the phone, his number is the most recently dialled, they occasionally chat, and from the few threads you have read, it is hard to define the kind of relationship they have.
But this day, you have evidence of a side of your wife you have never seen.

For a woman who is pretty reserved half the time, the chats were a revelation. And here is the dilemma, there is nothing incriminating, suggestive yes, but nothing that cannot be dismissed as petty flirting. Nothing you are not guilty of.
“Who is Tom?” you ask her.
There is a look of shock, then bewilderment, then a casual, curt answer.
“He is a friend. Why?”
Carol can make a good actor. She asks the “why” with all the innocence, and acting not alarmed at all, yet she knows where it is going. You decide to be passive aggressive, to see how that will work.
You sleep. It is not the first time, you have had this discussion.
You want to see how the silent treatment will work. And for two days, that is what you offer her, but she looks unperturbed and she has a way of making you feel like you are being childish.