A new report from Zelle finds that 46% of Gen Z currently owe friends or family more than $1,000, and 30% owe $2,500 or more. Nearly half, 47%, say they’ve gone into debt covering a group expense they expected to be repaid for, compared with 13% of Boomers.

Dr. Traci Williams, a clinical psychologist and financial therapist, said in an interview that the reluctance to settle up often starts before the trip even happens. “It’s really uncomfortable to have money conversations with people that you’re close to, and so they may not hash out what the payment arrangement should be before they front the cost,” she told Fortune. The person who organizes the trip is usually the one left holding the bill, she said, because nobody agreed on repayment terms beforehand.

“There’s a lot of assumption that happens, and so making the expectations clear and talking through it can really help.”

The Zelle report is based on two online surveys: one of 1,000 U.S. consumers age 18 and older, and the other of 1,000 “super-users,” or people who use Zelle at least four times a month. Breaking it down by generation, the survey found Gen Z spends more than any other generation at major group events—37% report spending over $2,500 per person on things like concerts, sporting events and group trips, the highest share of any age group.

But repayment timelines lag. According to the survey, only 28% of people who borrow for shared expenses say they repay immediately. And among Gen Z, 18% say it can take up to a month, 10% say two to six months, and 11% say more than six months.

Avoiding heavy conversations

Williams said part of the problem is simply how distracted people are. “It’s a whole lot easier to spend than it is to think through the process, including repaying other people,” she said. “People are pulled in multiple directions… we can forget, we can delay, we can put things off, we can have difficult conversations that we are avoiding.”

The report calls this pattern “payment avoidance,” in reference to a tendency to delay, ignore or withdraw from money conversations rather than have them. Twenty percent of Gen Z who owe money say they’ve muted or ignored a group chat to avoid paying someone back, and a smaller share, 7%, say they’ve stopped hanging out with the person they owe altogether.

But that avoidance is leaving a tangible impact on most respondents, regardless of age: 82% of Gen Z said owing money causes them stress or anxiety, compared with 71% of all respondents and 64% of Boomers. Being owed money weighs on people too: 59% of Gen Z said that stresses them out, compared to 46% of Boomers. Nearly half of Gen Z (48%) agreed that delaying repayment is itself a form of avoidance, and a third said settling up causes them stress or anxiety outright, roughly triple the Boomer rate on the same question.

Sometimes it leads to real life relationship problems, with 69% of Gen Z saying repayment issues have affected a friendship, family relationship or romantic one, and 14% saying a dispute has ended a friendship outright. Millennials report an even higher rate on that last measure—19% say repayment problems have cost them a friendship.

Digital tools may help with narrowing that gap, Williams said, saying it speeds up repayment—or makes avoiding it that much harder. The report backs that up: 76% of frequent Zelle users say they pay people back faster since adopting the app, including 86% of Gen Z.

“If it’s cash, how many people are walking around with cash, and then you and your friend are like, ‘Oh, I’ll get you back,’ and it just delays and delays,” she added.

Still, Williams urged patience with friends who may treat money differently. “The way that I view money is not necessarily the way that you view money,” she said. “It’s important in our friend groups to try to understand the nuances that exist within the group.”