She posted: "Happy Birthday to my best friend, the ♥ of my life, my soul!!!! I love you beyond words!"
Kim also posted numerous photos of the two together in a variety of romantic settings.
The reaction from her followers was decidedly mixed, with one writing, "I thought Kris was the love of your life?... Wait I thought that was Reggie....wait I thought that was Ray-J....wait I that was Damon Dash....oh never mind..."
And from another, "says the girl that vows at her wedding till death do us part or was it till what can i do to get T.V ratings?"
Kim is due to deliver the couple's baby next month. She and their daughter will join the rapper on European tour later in the year.