Arnold Schwarzenegger and his ex-wife Maria Shriver reunited for a family affair. 

The pair celebrated their son Patrick’s 29th birthday, as the actor took to his Instagram to post the special family photo. 

"Thx for the birthday wishes! 29! Crazy! Time flies," Patrick captioned the series of shared images.

In the first photo, Patrick holds a dessert plate that said "happy birthday," featuring some sweet treats and a candle. On the left side, his mother places one hand on her son’s shoulder while on the other side, the "The Terminator" actor poses closely with his family. 

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The three are all smiles while they celebrated the 29-year-old’s birthday.

In the second snap, Patrick is shown cozying up to longtime girlfriend Abby Champion, with a beautiful sunset in the background. The couple have been together since 2016.

Arnold Schwarzenegger Maria Shriver

Arnold Schwarzenegger and Maria Shriver reunited to celebrate their son Patrick’s 29th birthday, as the actor took to his Instagram to post the special family photo.  (Getty Images)

The Hollywood actor is also seen posing with a set of blue, yellow and gold balloons and another birthday cake in the set of Instagram photos.

Arnold Schwarzenegger and his son Patrick Schwarzenegger are seen in 2017.

Arnold Schwarzenegger and his son Patrick Schwarzenegger are seen in 2017. (Photo by Gisela Schober/Getty Images for GQ)

Shriver also shared a sentimental video montage on her social media in honor of her son’s birthday. 

The lengthy caption read "Happy, happy birthday, my beloved @patrickschwarzenegger! You are an amazing son, and I love you so much. You are smart, kind, loving, caring, fun, and funny… Join me in wishing Patrick a happy birthday!"

Maria Shriver Arnold Schwarzenegger

Maria Shriver filed for divorce from Arnold Schwarzenegger in 2011 after 25 years of marriage, citing "irreconcilable differences." (Photo by Angela Weiss/Getty Images)

Schwarzenegger and Shriver share sons, Patrick and Christopher, along with their daughters, Christina and Katherine, together. 

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The 66-year-old journalist filed for divorce from the 75-year-old former California governor in 2011 after 25 years of marriage, citing "irreconcilable differences."

Shriver and Schwarzenegger's property settlement has kept the divorce from being finalized all these years.

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Schwarzenegger also has a fifth child with his former housekeeper Mildred Patricia Baena, named Joseph.