NEW YORK ( TheStreet) -- Sharing expenses between friends and family is bound to cost you more money and hurt your relationship. 

A PayPal  (PYPL) study found the average respondent was owed $450 by friends and family, totaling $51 billion. The survey of more than 4,000 people in the United States, Canada, Germany and Australia also revealed one-third of respondents saw a relationship go south over IOUs. That's because people feel awkward about asking friends and family to pay up for their share of the expense.

"The tension that a person feels when they have someone who owes them money is part of what's preventing them from actually asking to get the money back," said Dr. Ryan Howell, associate professor at San Francisco State University.

Instead of having an awkward conversation with your friend, reminding them of how much money they owe you, Howell points to the convenience of a peer-to-peer lending platforms, such as Venmo or PayPal.me.

"That can actually intervene in a way that it allows you to ask for your money back, without having to actually ask for your money back,' he said. "It will give them notifications that they owe you money."

The study found 79% of U.S. respondents found peer-to-peer lending platforms save time, while 65% described them as 'liberating."

"People feel [peer-to-peer lending platforms are] a little bit less offensive and intrusive than face-to-face conversations," Howell added.

But technology can only go so far.  

If someone doesn't have the money to pay you back, Howell says the strategy then turns to psychology. The borrower should be vocal and communicate why they can't pay, he said.

"The problem is, while the lender is feeling angry, frustrated and agitated, the borrower is feeling guilty and ashamed and so they don't have a conversation," he added.

Even if you agree to split various expenses, be prepared to cover the entire expense on your own, or risk letting money interfere with a relationship.

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