If he doesn't want her to have it, then he needs to make sure it is never co-mingled with marital assets. If the money goes into a separate account (in his name only) and he never combines any marital funds into that account, then he should be OK, but it's worth talking with an attorney and/or financial planner if it's a significant amount of money. Divorce issues aside, there are a lot of issues involving taxes (for example) that can be very expensive if handled incorrectly.
Or, you could set it up with the money going into a trust. Properly designed, that might do the trick.