06/20/2011 04:24 pm ET Updated Dec 06, 2017

Arnold Schwarzenegger's Father's Day Plans: Spends Day With Son Christopher

It was a lonesome Father's Day for Arnold Schwarzenegger.

The embattled former California governor had lunch with his 13-year-old son Christopher at Marmalade Cafe in Malibu, but the rest of his children--Patrick, Katherine, and Christina--were absent.

Patrick, who is vacationing with friends in Greece, gave his Dad a twitter shout out instead.

"#happyfathersday to all the dads out there! Shout out to my dad and the best father i could ever ask for. Love you so much always!" he tweeted.

Schwarzenegger's estranged wife Maria Shriver--also absent from the Father's Day festivities--spent the weekend shopping for antiques and attending a U2 concert in Anaheim, during which Bono serenaded her.

"For Maria Shriver who's here tonight," he said before singing "Pride (In The Name Of Love)."

Shriver and Schwarzenegger separated in early May amid revelations that he fathered a child with former household staffer Mildred Patricia Baena.