Wife / Girlfriend rage
Tell her your going to buy a $1200 video surveillance system to catch the SOB that vandalized your car, and remind her that you all are going to have to pull the belt a little tighter for the next 3 months to cover the cost...assuming she knows you didn't see her do it. If she doesn't bat an eyelash at that, just stop the money flow anyway but as a common law husband you may get sued for support, that sounds like a CA/NY kind-of issue.