Over the weekend, Michael Phelps announced his engagement to Nicole Johnson.
The more we learned about Johnson, the more this began to feel like a relationship of convenience - an attempt to rebuild Phelps' shattered reputation in the wake of a DUI arrest and a number of bizarre allegations about his sex life.
Now, just days after their triumphant engagement announcement, the house of cards that is Phelps' and Johnson's relationship is threatening to come tumbling down, thanks to a surprising revelation from one of Phelps' alleged mistresses.
Earlier today, an Instagram user named Dana Shapiro posted a photo of what she claims is Phelps' penis, along with a caption reading, "Michael sent this to me."
Shapiro seems to have taken her affair with Phelps public in response to the swimmer's engagement announcement.
From the moment Phelps and Johnson reconciled after his recent stint in rehab, there were rumors that the relationship would outrage the many other women with whom Phelps was engaged in sexual relationships.
Phelps dated Taylor Lianne Chandler in the weeks before his arrest, but he reportedly cut ties with her after completing his treatment program, and the jilted PR specialist has since publicly expressed her doubts that Phelps is capable of monogamy.
Rumors of Phelps cheating on Johnson began to circulate within days of their latest reconciliation. (The couple has dated on and off since 2008.)
Now that Phelps is engaged and flaunting his new romance on social media, many expect that other women will come forward with claims that the beloved Olympian is far from faithful to Johnson.
So is Shapiro just the first in a parade of mistresses to rival Tiger Woods', or is she simply an angry ex looking for revenge? Has Phelps put his philandering ways behind him, or is Johnson in some ugly surprises?
Stay tuned to find out how this one plays out...