True. Even if ETH price would decrease, I doubt any borrower would adjust the repayment.
But, in such case, if I were lender/borrower, I would definitely try to have a discussion and would look for flexible amount (in case, I wouldn’t be able to repay this amount, since the loan amount was small).
Just imagine, you have borrowed 1 BTC when BTC price was $10k. You earn $500/week and planned to repay the loan within 20 weeks. But when BTC increases to $60k+, it's not anymore possible for you to repay the loan within 20 weeks, nor even within a few years. Just sharing possible reason of the default.
Lenders and lendee probably knew the risks already that's why they still lend and borrow. These people are the one who believe 1 BTC = 1 BTC and you won't gain loss if you don't sell, although some offer USD rates which is more understandable although offer higher interest rate since this will always be a disadvantage to the lendee.
In anyway, this is not the first time OP experience their lenders defaults, so i guess their decisions will probably still the same.