Mary-Kate Olsen planning marriage after Nate Bowman signs pre-nup?

If you believe all the rumors, Mary-Kate Olsen is about to get married…and she’s in full lockdown mode.

Her reps say it’s phony, but the word is the 23-year old star is planning to get hitched to her new fiancee, Nate Bowman. The two got engaged during a romantic break in Paris, France a few weeks ago, and plans are in hand for a wedding next year.

But Mary-Kate is insisting a pre-nup’s in place, and that’s causing some talks.

Thought to be worth in the region of one-billion dollars, Mary-Kate wants Nate to be her new hubby, but she also wants to protect all her cash from the downside if the marriage goes sour.

The pair first got together in 2008 after being hooked-up by friends and it now sounds like Nate has scored a home-run, “There were plenty of guys who came before him. But Mary-Kate wants to move on to what really counts – getting married and having children,”  a close friend explains.

For his part, Nate’s friends say he can certainly see himself married to Mary-Kate, but they are advising him not to sign any forms, “If they do marry and it ends in divorce, he should walk away with a big chunk of change,” one pal told the Enquirer. “What’s a payout of, say, $50-million to someone worth more than nine-hundred?”

But big sister Ashley doesn’t see it that way, “Ashley is deeply invested in their success and loves Mary-Kate. She knows a prenup is important and would certainly look down on Nate if he contests it,” an insider confirms.

And that’s the story so far. It may well be true, but MK’s reps say it isn’t. Keep checking in and we’ll bring you the rest…