The scheme in the OP would only make sense if you have more faith that your relative won't screw you over than you have hope that your marriage will last. Just marry under a prenuptial agreement- perfectly normal and doesn't depend on deceiving your spouse. Or alternatively, don't marry at all.

To be honest I can't imagine myself marrying a woman who has no education or job skills and would be financially dependent on me even if we decide to break up, but maybe that's just me.