The 32-year-old reality TV star, who is set to give birth to her first child with the rapper early next month, publicly declared her love for her boyfriend of more than one year, reported Us magazine.
The 'Keeping Up with the Kardashians' star posted a heartfelt message on Twitter, writing, "Happy Birthday to my best friend, the love of my life, my soul. I love you beyond words."
The brunette beauty also attached a photo collage, featuring several pictures of the couple looking madly in love together.
"He doesn't want Kim to think about trying to do something big for him on his birthday when she's pregnant. All he really wants for his birthday is peace of mind for him and Kim," a source said.