"Money is one of the top reasons people argue over things," Stanley Corey, a certified financial planner and managing director at United Capital in Great Falls, Virginia, told Business Insider.
If one spouse is hiding money, making large purchases without discussing it with their partner, or buying things that don't benefit the marriage, such as a boat or a new car, it leads to distrust and tension. Overspending and taking on debt can also put stress on a marriage, Corey said.
"It comes down to the breaking of trust," Corey added. "If you're carrying a lot of debt, it creates a lot of anxiety. Money is a very emotional issue."
Newman said that sometimes, someone who's guilty of breaching their spouse's trust will all of a sudden become very generous with gifts or vacation plans. That can also be a red flag.