Teen Mom 2's Briana DeJesus, Javi Marroquin and Kailyn Lowry
Marroquin said in October he and co-star DeJesus are dating. He was previously married to fellow cast member Kailyn Lowry and share a son, Lincoln.
Bachelor in Paradise: Dean Unglert, Kristina Schulman and Danielle Lombard
Unglert strung both women along on season three in 2017 and then chose Lombard. Schulman then left the show and Ulgert ended up changing his mind, telling Lombard that he loves Schulman. He and Lombard broke up, then rekindled their romance briefly after production ended. The three all appeared together on The Ellen DeGeneres Show in September. There, Ulgert said, "I see now looking back I could have handled things much, and I did handle things pretty poorly."
Jersey Shore: Mike "The Situation" Sorrentino, Sammi "Sweetheart" Giancola and Ronnie Ortiz-Magro
On episode 2 of Jersey Shore's debut season, titled "The Tanned Triangle," Mike got upset when he saw Sammi hooking up with Ronnie.
The Real Housewives of Orange County's Jo De La Rosa, Slade Smiley and Gretchen Rossi
After Smiley and De La Rosa ended their engagement, he pursued a romance with Gretchen Rossi, and De La Rosa was not having it.
Dancing With the Stars Peta Murgatroyd, Maksim Chmerkovskiy and Karina Smirnoff
In 2009, years before he dated Murgatroyd, his now-wife and mother of their son, Chmerkovskiy was engaged for nine months to fellow Dancing With the Stars pro Smirnoff. The two remain friends and the three have often starred on the show together. Smirnoff left the series in 2015.
Flavor of Love's Flavor Flav, New York and Deelishis
The rapper chose Deelishis (Chandra Davis) over New York (Tiffany Pollard) on season two of the VH1 dating show. New York then starred in her own spinoff, I Love New York.
The Real Housewives of New York City' LuAnn de Lesseps, Tom D'Agostino, Sonja Morgan and Ramona Singer
Triangle? More like a quadrangle! Before the Countess and D'Agostino got engaged (and married) in 2016, he reportedly dated her co-stars Morgan and Singer. De Lesseps and D'Agostino filed for divorce in August 2017 after seven months of marriage. His infidelity, involving other women, was a major storyline on the show.
Laguna Beach: Kristen Cavallari, Stephen Colletti and Lauren Conrad
Cavallari has said that Laguna Beach producers wanted to focus on a love triangle involving her, her boyfriend Stephen Colletti and Lauren Conrad.
The Hills: Audrina Patridge, Justin Bobby and Kristin Cavallari
Despite the drama that played out on TV, Cavallari revealed on Bravo's Watch What Happens Live in 2012 that her relationship with Justin Bobby on The Hills was fake.