Some people who borrow money can’t sleep unless they have paid their dues. However, there are also those who borrow money and don’t expect to pay. When the lender asks them to pay up, they get angry and the relationship is broken.
My own philosophy is to lend the amount I can afford to give away. If the borrower pays up, well and good. However, if he/she suddenly feigns forgetfulness, I have no problem with that, and I will just charge it to experience. Furthermore, that also serves as insurance that when the same person approaches me to borrow again, I can always say, pay the first loan first and I can lend you another.