The Big Bang Theory 's Johnny Galecki and Girlfriend Alaina Meyer Split

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Johnny Galecki and Alaina Meyer are going their separate ways.

A source tells PEOPLE the two have split and are co-parenting their son Avery, who will turn one next month.

The Big Bang Theory alum, 45, and Meyer, 23, started dating in 2018. They announced Avery's arrival in December 2019.

"With full and grateful hearts we welcome our beautiful Avery into this incredible world," Galecki captioned a photo of the newborn's hands on Instagram. "Thank you for all of your love and support."

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The then-couple first revealed Meyer's pregnancy in May 2019.

"We are absolutely over the moon to announce that we will soon be welcoming a little one into this crazy and wonderful world," they told PEOPLE in a statement. "There truly is love out there for all. We hope ours is the ember of yours, as we feel yours is the ember of ours."

Recently, Galecki and Meyer have been absent from each other's social media pages. Their last posts were both in April 2020, celebrating the Easter holiday.

"Happy belated Easter, from us to you," Meyer captioned a photo of the couple with baby Avery. Galecki shared a similar photo: "A heartfelt (& belated) Happy Easter from the three of us to you."

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The two were first linked in August 2018, when they traveled together to Tahiti Beach in the Bahamas. While neither tagged in photos during their stay, Galecki shared a photograph of himself hugging a woman with a thigh tattoo on the beach.

That September, they officially went public with their relationship by posting an Instagram photo from a night out together. Two months later, they made their awards show debut at the 2018 E! People's Choice Awards.

The following month, engagement rumors began to circulate after the pair was seen wearing rings. Meyer set the record straight at the time, posting a photo of her and Galecki with the caption "#notmarried."

Galecki dated his former Big Bang Theory costar, Kaley Cuoco, for two years before breaking things off in 2010.