The 71-year-old actress has been dating music producer Richard Perry, 67, since the summer (09) and they were recently rumoured to have announced their engagement at a dinner party in California.
But Perry is adamant they don't have plans to walk down the aisle any time soon.
He tells British magazine Hello!, "She (Fonda) thinks it's a bit too soon (to marry), and no doubt, she's right, although I said from the beginning we should make our relationship a priority."
But Perry is convinced Fonda might be planning their nuptials in secret, adding: "Sometimes the thought pops into my head that Jane will organise a wedding as a wonderful surprise for me."
Fonda has been married three times before - to late French director Roger Vadim, former politician Tom Hayden and media mogul Ted Turner.