The Ace Ventura actor is currently dating the 30-year-old student, and reportedly made the decision to wed on his 50th birthday in January, reports Star.
"Jim is going to propose! He's absolutely crazy about Anastasia and couldn't be happier," a source said.
Carrey split from Jenny McCarthy after five years together in April 2010, with the actress later saying that he had "stopped being fun".
The insider described Vitkina as "really smart", adding: "But what he likes best about her is her sense of humour. She makes him laugh - Jenny would drive him to tears.
"Jim confessed to Anastasia, 'It's not always easy being with me in more ways than one'. But he added, 'I promise to make it worth your while'."
Jim Carrey has married twice before, most recently with Dumb and Dumber co-star Lauren Holly from 1996 to 1997.
The comic actor has recently been linked to a Bruce Almighty sequel.
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