^^^ Good explanation right there. He's not paying the bills with YOUR money - you gave that money to him to pay for your part of the bill - therefore, that money is now HIS - it's none of your business what he does with it. In the end, you're all still paying for your shares, except him, who get's it paid for by his mom. You wouldn't gain or lose anything if his mom didn't pay, so what's the difference?