Charlotte Casiraghi Leaves Her Much Older Boyfriend and Heads to Monaco with Their 17-Month-Old Son, PEOPLE Confirms

Charlotte Casiraghi is nursing a broken heart – and a sore back after falling off her horse in a jumping competition today.

The 28-year-old – who is eighth in line to Monaco's throne –has abruptly split after three years with French comedian-actor Gad Elmaleh, 44, PEOPLE confirms.

The couple are parents to a 17-month-old son, Raphaël.

"It's sad," a source close to the couple tells PEOPLE, confirming reports that broke in the French media on Thursday. "Mostly, this is a couple that drifted apart over their careers.

"He wasn't around enough – and she wanted a father for her son."

With a 16-year age gap, the princess – whose mom is Monaco's Princess Caroline and grandma is the late American actress-turned-Princess Grace Kelly – and the comedian were an unconventional and extremely private couple. After meeting at a party in late 2011, the pair embarked on a discreet relationship that quickly went from whispered affair to tabloid favorite.

Their coming-out was a public appearance together in March 2013 alongside members of the Monaco royal family at the Bal de la Rose – but they continued to maintain a quiet profile, even as Casiraghi prepared to give birth to their son in December that year.

Never married, the couple split their time largely between France and Los Angeles. Their backgrounds and interests were wildly divergent: Casiraghi is a competitive horse jumper and Gucci model. Elmaleh is a Moroccan-born, French stand-up comedian and actor who appeared in 2011's Midnight In Paris. He has a 15-year-old son, Noé, from a previous relationship with French actress Anne Brochet.

Although he rarely discusses his private life, Elmaleh opened up to PEOPLE about his relationship with Casiraghi in October 2013, saying he was the "happiest man" and "lucky" to have her in his life. Many compared their romance to another similar long-term relationship between Casiraghi's own mother and French actor Vincent Lindon.

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"She's a smart and very intelligent girl who has a lot of humor," he said. "We share the same observations about life. When we are somewhere, she says, 'Did you look at that? Did you observe that? What did you think about that?' And then we have a good exchange … She's one of those people who always tells the truth.

"You can talk about philosophy and make stupid jokes with her," Elmaleh added. "We go see art or she will go crazy over a TV show and laugh out loud with me about a stupid gag. So this is important for me to mix all that and we have real conversations and share things. I'm the happiest man – really, I am. I am lucky to be with her."

Rumors of discord have circled the couple for weeks – even before last month's Cannes Film Festival, where Casiraghi turned up solo on the red carpet. On Thursday, French outlet Voici revealed that Charlotte had returned to Paris after the festival but settled in a luxury hotel instead of returning to the couple's apartment.

Sources tell PEOPLE that two men, including a chauffeur, removed Casiraghi's things from the couple's Paris apartment this past weekend, while mother and son flew to Monaco on Monday.

On Thursday, Casiraghi was in St. Tropez preparing to participate in this weekend's Athina Onassis Jumping competition. She suffered a fall from her horse and was seen rubbing her back as she got up.

Elmaleh is expected to return to the U.S. later this month.

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