Think back on the last fight you had with your partner. Chances are good that it involved money. Arguments about money occur at least monthly for about one-third of couples, according to a 2016 study by the financial services company Ameriprise Financial Inc. Arguments about financial issues last longer than fights over parenting, sex, or in-laws, and they take much longer to recover from, according to researchers at Kansas State University. Moreover, the same researchers found that conflict about money is the best predictor of the probability of divorce. Find out what forms of financial deceit or infidelity — where they’re not being upfront about their spending or money sources — spouses may engage in and what to do if you encounter them.Carol Povenmire, Ph.D., is a licensed psychologist with a practice in Pasadena, California.