On Monday, January 24, the former Disney Channel star, 33, was seen stepping out in Beverly Hills with a diamond ring on her left hand, implying that she was set to tie the knot with the Home Alone actor, 41.
Song and Culkin welcomed their little boy in April of last year with the Uncle Buck star telling the outlet the pair was "overjoyed" about the birth of their son.
The couple began dating in July 2017 — where they were photographed on dates at Craigs, an Italian restaurant in Los Angeles — after meeting on the set of Changeland in Thailand.
"Happy 40th birthday to this magical being," the Suite Life Of Zack and Cody star wrote alongside a picture of the two. "I could sit here and write endlessly about how wonderful, kind, loving, genuine, loyal, honest, brilliant and hilarious you are, and how grateful I am that I get to share and do this life thing with you."
"But firstly, that would take me an eternity and secondly, you won't even see this because you don't ever use instagram. Hahaha," Song continued. "My unicorn that I never thought could exist, I am luckiest person in the world because I am loved by you."
"This one's a good one, so I'm probably going to put some babies in her in a little bit," he said, adding. "I mean, we've definitely been practicing."