I dont feel like it should be an issue, if shes truly the one and feels the same about you, then signing a prenup shouldnt be a problem, just make sure you explain things clearly and that its a "just in case" type of thing, like insurance, you hope you wont need it, but its there if you do. I know Ive heard that lawyers can cut through one, but I would think that a good lawyer could also write up a pretty water tight one? 

Its not much different than watching a family squable over inherited ground, she could be the sweetest girl you ever met right up until its over, and then she could make Satan himself hide in fear. All it takes is one of her friends to mention all the $$$ you have in assets and how she should "get even" with him, even if he did nothing wrong. It happens all the time with children, the woman will use the kids as revenge and profit.

Ive already been very clear with my little lady that if and when the day comes, there will be a prenup, and shes fine with that.