My husband asked me to sign a prenup on the advice of his attorney and accountant. I refused. I agree with squirrley that it would be wrong to take that which I wasn't entitled to. In the end, my husband decided to trust me, and I think that was a smart gamble on his part. He had to trust that I am a person of good moral character who wouldn't take that which I wasn't entitled to, and I had to trust he is person of good moral character who wouldn't present me with such extreme circustances that a divorce would be necessary (I personally don't really approve of divorce except under extreme circumstances). had he insisted on the prenup, I definitely would have walked.
EDIT: after we married, we got rid of the accountant.