Rosie O'Donnell and Tatum O'Neal Are 'Romantically Involved': Source

In an unexpected summer romance, Tatum O’Neal and Rosie O’Donnell are dating, a source tells PEOPLE.

“They are romantically involved,” says the source. “It’s a bicoastal relationship.”

News of the under-the-radar relationship comes just months after O’Neal, 51, revealed exclusively to PEOPLE that she now dates women.

Five Surprising Facts About Kevin McEnroe's New Novel

In this week’s PEOPLE, Kevin McEnroe, the son of Tatum O’Neal and tennis great John McEnroe, opens up about what it was like to grow up in his troubled family – but it’s his new novel he really wants to talk about.

Griffin O'Neal: 'My Whole Family Has Been Destroyed to Smithereens From Addiction and Alcoholism'

Griffin O’Neal, the son of actor Ryan O’Neal and brother of Tatum O’Neal has struggled for years to break free from one of the most famously dysfunctional families in Hollywood.

“My whole family has been absolutely destroyed to smithereens from drug addiction and alcoholism,” says Griffin, 50. “The common denominator is drugs and alcohol and depression and it’s a never-ending cycle. I had to walk away from all of it. I’m done.”

Tatum O'Neal on Redmond O'Neal: 'I've Never Seen a More Scary Side of Addiction'

Redmond O’Neal, the only son of Ryan O’Neal and Farrah Fawcett, has struggled with a serious drug addiction for many years. Now that a Los Angeles Superior Court judge has revoked his probation and issued a no-bail bench warrant for his arrest in April, his half sister, Tatum O’Neal, admits she is extremely worried for his safety – and his life.

Growing Up McEnroe: The Untold Story

It’s been a long road for the three children of Tatum O’Neal and John McEnroe, whose explosive marriage was marred by her addiction battles, his famous temper and their long, drawn-out custody battle. Today, their three children, Kevin, 29, Sean, 28, and Emily, 24, say they have found a new understanding of their experiences growing up in one of Hollywood’s most famously troubled families.

Tatum O'Neal on Ex-Husband John McEnroe: We Have No Relationship, But 'There Is Respect Now'

After Tatum O’Neal split from tennis ace husband John McEnroe in 1992, years of turmoil followed. Amid claims and counterclaims of drug use, violent tempers and escalating fights, their custody battle over their three children became an all-out war.

Tatum O'Neal: 'I'm Dating Women Now'

Kevin McEnroe on His Mom Tatum O'Neal: I Thought She Was Choosing Drugs Over Us

Arrest Warrant Issued for Redmond O'Neal, Ryan O'Neal and Farrah Fawcett's Troubled Son

Redmond O’Neal – the son of actors Ryan O’Neal and the late Farrah Fawcett – is in trouble again.

Los Angeles Superior Court Judge Keith L. Schwartz revoked O’Neal’s probation and also issued a no bail bench warrant for his arrest in April after Redmond’s probation officer notified him about the violation, according to court documents obtained by PEOPLE.

John McEnroe and Tatum O'Neal's Son Kevin Arrested for Drug Possession

Kevin McEnroe, the oldest son of tennis champ John McEnroe and his ex-wife, actress Tatum O’Neal, was arrested on drug charges in N.Y.C. on Tuesday.

McEnroe was stopped by cops in downtown Manhattan after he was allegedly seen buying drugs, the New York Post reports.