You are right and the campaign on which the user was still active. So, there was no chance to earn less than 100$ per week. I can't imagine a healthy-minded person can act like Edwardard did.
His activity looks weird, even before he asked you for a loan, he wasn't making a maximum of his income through that signature, he had periods when barely posted so if he really would have needed that money he would have got them just from the signature even without taking the loan.
The family issue thing doesn't hold water, you're not throwing away a source of income when you're in debt over family issues, so it's either that he lost the money and thought it was not worth it anymore to work for 3 months to pay it back and decided he had enough!
But seriously, you should really limit the sums you're giving away with no collateral, or at least make a deal with them and the managers to receive at least 50% of their weekly payouts, one of these things and you're what, two-three months in red?