Sounds to me like he's thinking with his groin and trying to impress his gf without considering the long-term conseqs. If he really is earning as little as he says, and is relying so heavily on loans, then you can rest assured he's not just on borrowed money but also borrowed time. At some point (maybe not today, maybe not tomorrow, but some day...) he will be forced to face the fact that the original loans plus exorbitant interest fees are towering above him and far too much for him to handle.
He may well then bury his head in the sand and hope the problem will go away, but you and I know it won't. His gf and your kids will then realise what an ass he really is, and he'll probably end up either having to declare himself bankrupt - in which case he'll be forced to sell all those lovely assets and no more loans, matey! - or he'll end up on one of those humiliating sort-your-life-out TV progs where people on benefits with a designer clothing addiction end up looking like right monkeys while the experts help them sort their lives out.
I know none of this changes your financial situation, but it might be a good opportunity to explain to your children the importance of financial wisdom and dangers of living on credit.