“Nothing is ever really lost. welcome back,” the actor said in the post, tagging her fiance's song “Last November."
The couple spoke about experiencing a miscarriage more than a year ago. They announced their engagement in 2022.
Fox, 38, was married to actor Brian Austin Green from 2010 to 2021. They have three sons together.
Machine Gun Kelly, 34, whose real name is Colson Baker, has a daughter from a previous relationship.