A House of Commons select committee has been told that William is speaking openly about his future plans with Kate, according to the Mail's story.
William, 24, and Middleton, 25, were first spotted together around Christmas 2003, and the two have been seen together regularly since then.
A well respected royal photographer, Arthur Edwards, reportedly told the Members of Parliament, "She's in love with Prince William. I'm sure one day they'll get married.
"I have talked to him about that and he's made it clear ... he wants to get married."
Clarence House refused to comment on any possible plans, saying: "Prince William has no plans to get engaged."