Business and pleasure are a dangerous combination. They can add fuel to a hot sex life when the business is going well, and dampen the wateriest Hallmark card when business takes a turn for the worse. There’s a reason that family businesses become such a source of lifelong conflicts for those in them.
So, you need to either strike a balance knowing your girlfriend, yourself and your business, or you need to choose to whether to put your business or your girlfriend first.
If you can spare the $10,000/year, then you may want to write it off as the cost of doing business with your girlfriend, and from this point on, clarify your business agreement with her in writing so that you’re not left in this position in the future where the question of stealing is on the table. Contracts eliminate those questions.
If you’re too angry about her “stealing” the money from your business, and you think that this is a character flaw that is a deal breaker in your relationship (because [b]I guarantee you’ll see this behavior again down the road with her[/b]), then it’s time to call the relationship quits.
If you can see that she’s got a point, and you didn’t take responsibility for seeing this situation earlier, then accept your mistake, admit she’s right to take this money and change your own business behavior for future.
I hope that helps!