Partisan politics aside, former Republican presidential candidate Herman Cain did something no spouse should ever do.No, I’m not talking about the alleged 13-year extramarital affair with Ginger White. Cain has denied her claim.But we do know that Cain had what could be called a financial affair.In various interviews, Cain has said he paid some of White’s monthly bills and expenses. He also has said his wife of 43 years didn’t know about the relationship or the payments.Cain, who has suspended his presidential bid, won’t disclose how much he gave White, but based on public comments from both of them, it wasn’t chump change.On MSNBC’s “The Last Word,” White described the help Cain was giving her.“He would help me monthly,” according to a transcript of her interview with host Lawrence O’Donnell. “Most times he would be travelling, and when there were several texts, it was just he and I trying to get our schedules together to where we could meet and he would, you know, help me out with money for bills and various things.”In another interview with The Daily Beast, White said she has accepted money from multiple men to help support her and her two children.If my husband of 20 years was regularly doling out our money to anyone without my knowledge, much less a non-related single woman, I would have to be restrained from cooking a big pot of grits and tossing it on him, as Tyler Perry’s trash-talking on-screen character Madea often advises wronged wives to do.Certainly, Cain’s financial indiscretion doesn’t justify violence.But what he did would make a lot of spouses hopping mad because it violated an important marital rule you should not be shelling out money on the sly.“My wife did not know about it, and that was the revelation,” Cain told the Manchester (N.H.) Union Leader. “My wife found out about it when she (White) went public with it.”Even if the Cains keep their finances separate, Cain should have disclosed to his wife that he was supporting White.And yet, Cain is not alone. So many others are having similar financial indiscretions in their marriage.The National Endowment for Financial Education found in a survey that 31 percent of people who combined finances with their significant other have committed some type of financial deception from hiding purchases to lying about the amount of debt they owed. Of those who practised deception, 58 percent say they hid cash from their partner or spouse.Eighty percent of spouses spend money their partners don’t know about, according to a survey last year by CESI Debt Solutions, a not-for-profit credit counselling organisation.In another survey conducted this year by CESI, 30 percent of respondents said they think financial infidelity is just as bad as sexual infidelity. Dishonesty is bad in either case.Like any devoted and respectful spouse, Cain should have avoided even the appearance of impropriety.And to further add injury to outrage, he waited days before going home to talk to his wife.That action generated an additional amount of indignation among some women I was discussing the situation with. As one of my friends said: “I come from crazy Southern women. Locks would have been changed. Stuff would have been on the front lawn.”If you want to avoid having your spouse changing the locks or hiring a divorce attorney, think about implementing some of the following rules:n Agree that neither of you will make large purchases or provide financial support to relatives, strangers or friends without first consulting the other.n Even if you keep separate accounts, it’s important to talk about your joint and separate expenditures.CESI’s recent survey found that 73 percent of married couples believe spending more than $100 without telling your spouse is not acceptable.n Agree that if either one of you wants to make a major purchase, both of you must vote in the affirmative.n Agree that there will be no financial secrets between you. No hidden bank accounts. No earnings that are not disclosed. No secret accumulation of debt. And lying by omission counts.In an interview with Sean Hannity, Cain said: “I’m a softie, and I feel sorry for people when they get in deep financial trouble, especially given the economy and people being out of work.”OK, then why the secrecy? Why didn’t his wife know about his so-called generosity?I think it was because he knew that what he was doing was improper. But as saints like to say, what happens in the dark will always come to light.Readers can write to Michelle Singletary c/o The Washington Post, 1150 15th St, NW, Washington, D.C. 20071. Her e-mail address is singletarym[AT]washpost.comComments and questions are welcome, but due to the volume of mail, personal responses may not be possible. Please also note comments or questions may be used in a future column, with the writer’s name, unless a specific request to do otherwise is indicated.