Why are they marrying someone who they don't trust? That sounds like an awful state of affairs and likely those marriages will not last. Don't most wedding vows include a line about being honest? Yikes to those marriages.
That doesn't make sense. Rationally, hiding that money in secret is a reason that the marriage won't work out. Hide that money, tell lies, be a scheming and awful person, and there will be a self-fulfilling prophesy of that marriage not working out.