DANNY DEVITO’s 30-year marriage to RHEA PERLMAN was torn apart because of the star’s workaholic ways and his infatu­ation with young women, say insiders.

After the couple announced their separation on Oct. 8, a source claimed: “Danny’s 67 but still flirts with women like he’s 20!

“He’s been living a totally sepa­rate life from Rhea for the past few years – producing, acting…and behaving like a horny frat boy!”

Insiders revealed that Rhea had grown fed up over Danny’s inces­sant flirting with much-younger women, including friends of their 29-year-old daughter, Lucy.

What’s worse, Danny – who was recently photographed cutting up with sexy actress “Vampire Diaries” star Kat Graham at an awards ceremony – even made small-talk with young women when he was out in public with his wife.

“It makes him look like a fool, and makes Rhea feel like one,” con­tinued the source.

While Rhea has finally reached her breaking point, the source was quick to note that the be­havior was nothing new for the former “Taxi” star. Two years ago, Danny was filmed cavorting with topless women at the Coachella rock concert in California. And in 2007, Rhea was humiliated when her husband signed a fan’s breast during an appearance in Florida.

The couple met in 1970, married in 1982, and are parents to Lucy and two other grown children – Gracie, 27, and Jacob, 24.

The 5-foot-tall actor has been enjoying a ca­reer resurgence since starring in the hit FX series “It’s Always Sunny in Philadelphia,” which just wrapped filming its eighth season. Danny spent the summer in London starring in a stage production of “The Sunshine Boys” – where he was rumored to have a girlfriend – while Rhea, 64, went it alone in Los Angeles.

“Rhea and Danny have been living separate lives for quite some time,” noted the source. “She would call Danny on set constantly, begging him to scale back, but he kept telling her that work was his first true love.”

Additionally, insiders say Danny has been hanging with a much-younger crowd lately, in­cluding 35-year-old Rob McElhenney – creator and star of “Philadelphia” – and Zac Efron, 25, his co-star in “The Lorax.”

“Danny regularly ditched date nights with Rhea to party with guys like Rob or Zac and their young friends,” said the source. “Danny loved the atten­tion he got from hanging out with a young crew. And he had a major wandering eye when Rhea wasn’t around.”

“Rhea had hoped they’d spend their golden years enjoying long trips together, being with family and doing the occasional film or stage project,” added the source. “But, sadly, it seems as if Danny chose work and play over his mar­riage. The split has actually been coming for some time – they talked about a separation back in 2007 and even divvied up some of their land assets last year.

“Now, Rhea has finally decided to start a new life – just like Danny has.”