Did LuAnn de Lesseps and Tom D'Agostino break up because of his ex Missy? Tom's flirtations with Missy during the RHONY finale marked another sign the marriage was in trouble.

We first met Missy earlier this season, when she spoke to Ramona Singer about her past relationship with Tom. Missy claimed that she was still dating Tom when he started seeing LuAnn. In fact, Missy said she only realized her relationship with Tom was over when she saw him kissing LuAnn at the Regency.

CLICK HERE FOR MORE ON LUANN AND TOM'S DIVORCE ...

Missy and Tom then had an awkward reunion at a party thrown by Ramona. Tom even told Missy that the ring on his finger made him feel like a "dog with a collar."

Watch Tom and Missy's first reunion on RHONY.

At the time, LuAnn seemed convinced that Tom and Missy were just friends. But they appeared quite flirty during the RHONY season finale, when they both attended a party thrown by Tinsley Mortimer. Tom even took off his microphone so cameras couldn't capture what he was saying.

Watch Tom take off his microphone on the RHONY finale.

Of course, this doesn't mean that Tom cheated on LuAnn with Missy. LuAnn has even said she doesn't think Tom had an affair during their marriage.

 "I do not think Tom cheated on me, definitely not," she told Page Six. "God knows he’s got himself in some trouble in the past, but I don’t believe that continued [while we were married]."

WHY LUANN AND TOM WERE MISMATCHED FROM THE START ...

But Tom's conversations with Missy just confirmed that he was not ready to settle down. He wanted to continue his single lifestyle, while LuAnn wanted Tom to act like a husband. And sources say that is what drove them apart.

"He wanted to live his bachelor's life too. He's never been married," a source told E! News. "She wanted a marriage, he wanted a part-time marriage."

No matter what caused LuAnn and Tom's breakup, she's clearly not dwelling on what happened. After announcing her divorce, she headed to Switzerland to take some time for herself.

FIND OUT ABOUT TINSLEY MORTIMER'S NEW BOYFRIEND ...

"She's still struggling, of course, with sadness and disappointment but she's trying to come to peace with it," a source explained to E! News. "She lived in Switzerland during her first marriage and it's where she raised her children," the source explains. "She feels comfortable and safe there. I think it's a reminder of who she was before the show and before Tom." 

Do you think Missy played a role in LuAnn and Tom's split? Let us know your take in the comments section below!