Owing money to a friend will concern, should the matter go to court, the issue of a valid formation of a contract. Without a contract and the rights granted by it there can be no successful claim.
Contractual formation can occur verbally but relies on four main criteria being met; offer, acceptance, consideration and an intention to create legal relations.
The first two criteria in your case would be satisfied: �do you want to borrow some money� (offer) �Yes please� (acceptance) The issue therefore relates to whether or not you have provided consideration and there is an intention to create legal relations. Of most importance is the intention to create legal relations.
Domestic (non-commercial) contracts have a presumption against an intention to create legal relations; whilst this can be rebutted, the courts will assume that by your friend lending you any money there was no intention to create a contract upon which they could rely, for lack of an intention to create legal relations.
As such whilst your friend may no talk to you it would be difficult for her to take you to court and assert a verbal contract unless she said words to the effect of �by lending you this money I intend to create a legal binding contract�. Moreover should the matter be taken to court it would be somewhat of a �he said she said� and proof of having a valid contract will be difficult to provide.