One in seven adults in debt has hidden their money problems from a partner, according to relationship charity Relate.
Some 14% of those with debt say they have kept it secret from a partner - and 7% of those with debt are currently hiding it - a report which highlights the links between debt and relationships found.
Feeling ashamed is the most common reason why people hide their money problems, with 51% giving this reason, followed by 46% who said they would be scared of their partner's reaction.
A third (34%) of those with hidden debts felt their partner had a different approach to money.
More than 4,700 people across Britain were surveyed for the report, titled In too deep: an investigation into debt and relationships, which is sponsored by Provident Financial.
Relate said there is a "relentless cycle" in which debt problems cause conflict, mistrust and relationship breakdowns.
Relationships can also contribute to people's debt problems and affect how they manage their finances, it said.
The report said one in six (16%) adults are currently in problem debt, meaning they find meeting financial commitments a heavy burden and/or have been missing payments for three out of last six months.
:: One in five (20%) has experienced the breakdown of a relationship with a partner where debt was either the main reason or a contributing factor.
:: Nearly four in 10 (38%) said it has had a negative impact on their relationship with their partner.
:: A quarter (25%) argue about money, debt, and/or other financial issues with their partner at least once a fortnight.
:: Nearly one in 10 (9%) said they argue with their children once a week or more, which is three times as likely as those not currently in problem debt.
Relate also spoke to hundreds of debt advice and relationship support professionals and their clients as part of the research.
The charity found 36% of debt advice clients said that relationship breakdown was a cause of their problem debt and 93% of debt advisers said personal and family relationships are important to a client's ability to manage debt.
Chris Sherwood, chief executive at Relate said: "Talking about debt can be difficult, especially if you feel ashamed or have different approaches to money, but keeping things under wraps can be problematic for the relationship and make the debt harder to manage."
The Treasury select committee recently launched an inquiry into household finances.
Committee chairwoman Nicky Morgan said: "As this important report from Relate states: 'Debt problems can be both a cause and a consequence of damaging relationship issues.'
"I know, from my work as a constituency MP how damaging persistent and unmanageable debt can be to family relationships and mental health."