It's been a memorable couple weeks for Lady Gaga.
First, the 28-year-old pop star got engaged to Taylor Kinney, her boyfriend of several years, and flashed her giant, 15-carat diamond ring to the world.
She followed that up with a Sound of Music tribute at the Oscars that was almost universally praised, with many observers calling it the highlight of the night.
Then, just yesterday, we learned that Gaga will star Season 5 of American Horror Story, thus capping off one of the biggest weeks of her storied career.
But what goes up must come down, and Gaga's winning streak may have just come to an end, thanks to these claims being made by Brittany Sackett ...
As in her fiance's ex-girlfriend Brittany Sackett.
Sackett claims her relationship with Kinney, the star of NBC's Chicago Fire, came to an end when she caught him cheating on her with Gaga.
She says she found out what was going on between them when Kinney called her accidentally during a makeout session with the Mother Monster.
Yes, Taylor was done in by the butt dial.
"Taylor was butt-dialing me at 2:30 in the morning," Sackett tells the Daily Mail. "Whatever he was doing shouldn't have happened while we were in a relationship.
"My boyfriend was making out with Lady Gaga."
"It sucked. I felt betrayed; who wouldn't?"
It's a valid question Brittany poses.
Sackett says Kinney came clean after he confronted her, and she's since forgiven him. Even so, her revelation could spell trouble for Gaga for a couple of reasons.
For one thing, Gaga fancies herself something of a feminist icon, and if she was aware that Kinney was in a relationship, her reputation might take a hit.
Even worse, however, is that old adage you know well.
"Once a cheater, always a cheater." How many times have we heard that one? More than we can count, both in celebrity news circles and in real life.
Will this saying now be ominously applied to Kinney and Gaga's forthcoming marriage? We hope not, but she's not the first person to be in these shoes.
Other celebrity wives who were mistresses first ...