I believe everyone had their own perceptions regarding the borrowing of money from a friend or relatives. Some people never borrow the money as it's against their pride. Trust me a needy person will never ask for money until and unless someone gives them by insisting. And few never return the money as it's their policy to have a loan and leave them alone but their ratio is quite little and can easily be judged.
However, Borrowing money from a friend and not returning him back can have a negative impact on your friendship while if it's returned on time then it doesn't harm friendship in fact it builds their friendship and Trust.
According to my perception, Borrowing money from a close friend or relative is normal. I still remember the situation when I badly needed the money to pay my utility bills. Actually I was unemployed at that time and asked my friend for help and we guys made a commitment to return the money as soon as I get a good job and that's what I did. In spite, He was delighted that I returned him on time. We still are pretty good friends and usually meet every week.
Furthermore, I also believe that borrowing money can harm friendship too if someone is lending money to his friend it probably means he trusts him but in return, if the next person doesn't pay him on time that means he breaks his trust. Trust needs a thousand moments to build but a matter of second to break.
In Conclusion, It is normal that friends lend money to other friends whey they need it. After all, this is friendship is all about. A wise man once said A Friend in need is the Friend Indeed.
Trust is very important in any relationship, be it marriage, business and any other form of relationship. "Be trustworthy".