Student debt is putting a damper on young Americans' relationship decisions, according to a new study from private lender LendKey Technologies.

About one-third of respondents between ages 18 and 34 say they might postpone marriage — or have already done so — until student debt is paid off, according to the study, which surveyed 1,037 U.S. adults who attended college. The study was given to USA TODAY exclusively.

That number shrank among older respondents. About 17% of those between 35 and 54 would postpone marriage and 10% of those 55 and older would delay it.

Debt also affected partner choices.

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Just over one-third of millennial and Gen Z respondents say a potential partner's student or credit card balances could affect their choice of a spouse, depending on the amount of debt. Twenty percent say they'd be fine with student loan debt but not credit debt, while 6% say the reverse.

Just 4% say any amount of debt was a dealbreaker. Roughly 36% of the people surveyed say debt wouldn't factor into marital decisions.

"Student debt is something millennials have to think about when considering marriage," says Vince Passione, chief executive at LendKey. "It's not just affecting their wallets, it's also affecting the way they view relationships."

A separate study shows that more than 50% of dating millennials don’t want to marry until their finances are in order, according to a recent survey from Credit Karma. Almost two-thirds of those surveyed millennials who were in a relationship have a separate bank account from their significant other. And nearly one-third say that keeping at least one bank account separate from their partner’s helps keep their relationship alive.

Borrowers of all ages currently owe roughly $1.5 trillion in student loans, according to the Brookings Institution. About 42 million Americans have student loans, which are the second-largest portion of household debt after mortgages.

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LendKey's survey also found a lack of financial literacy around student loans. Just 16% of respondents between 18-34 say they have "shopped around” for the best rate and terms for a student loan. By contrast, two-thirds overall shopped for the best rates and terms for cars, 60% for insurance and 57% for vacations.

The data suggests that students need a greater understanding of the loan process, says Passione of LendKey.

About 41% say they believed loans came from the schools themselves, while 14% incorrectly guessed angel investors are providing loans to the public. Millennial and Gen Z borrowers were more likely than older generations to believe that a government program will eventually relieve their burden.