Financial infidelity, described as financial secrecy or hidden spending, is a growing problem that frequently leads to divorce and substantial financial damage. Modern technologies, such as shopping apps and sports betting, have made it easier for spouses to conceal "unsavory spending" from their partners.

Divorce lawyers report seeing cases where one spouse improperly spends assets that belong to both parties. For example, one client discovered her husband had spent $20,000 monthly for over a decade to support another woman and child without her knowledge. This kind of financial deception, whether it's hiding debt, purchases, or secret bank accounts, is a major "trust buster."

The prevalence of separate bank accounts is increasing, with 23% of couples having no joint accounts in 2023, up from 15% in 1996. This trend, partly attributed to later marriages, can make it easier to hide financial activities. Both men and women are equally likely to commit financial infidelity, according to a 2019 Journal of Consumer Research study, with rates varying globally from 22.7% in the Netherlands to 53.7% in Turkey.

The consequences can be severe; for instance, Jessica Simon discovered her marriage was in trouble due to discrepancies in a shared checking account. Lawyers like Even Schein note that spouses are often shocked to find the shared marital assets are significantly less than they believed.