There is no definitive answer to this question as it can depend on the individual and their marriage. However, according to a study published in the journal JAMA Psychiatry, infidelity is common in marriages. The study surveyed 1,500 married couples and found that 39% of those surveyed had experienced infidelity in their marriage. Additionally, the study found that infidelity was more common in marriages with lower incomes and was more likely to occur in marriages where one spouse was physically or emotionally abusive.