On Thursday, Page Six ran an otherwise innocuous item about CBS Evening News weekend anchor Russ Mitchell getting engaged to girlfriend Karina Mahtani, an associate producer for the tiffany network's Showbuzz segments. The hook: They weren't telling anyone — and news of their road to nuptials came only when "a co-worker spotted the bride-to-be working on invitations for an engagement party."

We can imagine why the news-some duo kept their off-air romance a secret to the general public, but not even telling colleagues about their engagement? And not returning Page Six's phone calls to confirm? (The audacity!) Sounds off even to us, and we live in a world where exporting Us Weekly makes sense.

But this afternoon, things became clear when an insider shared the backstory. The reason Mitchell and Mahtani are so coy about their vows allegedly has something to do with your weekend anchor's third-party tyrsts. We're told that for more than a year, Mitchell has been seeing another women – even taking her out to public spots like Gabriel's and Brasserie Ruhlmann in Midtown and Cain Southampton – who he knows from his childhood in St. Louis (though she lives in Manhattan now, too).

We also understand that Mahtani isn't wearing an engagement ring. Meanwhile, CBS is supposedly fully aware of the threeway situation — as is Mahtani, and she is still ready and willing to marry Mitchell.