Some gay men believe that being married can rid them of their homosexuality. The wife has not been inadequate in any way and likely the gay husband married her because he truly cared about her. What's important to remember is that the husband's homosexuality is entirely his responsibility and has nothing to do with the wife. (If you're thinking that you can cure the gay by having your husband go to gay conversion therapy, read this.)
If the husband is honest with both you and with himself (read: How Do I Know If I Am Gay? Signs You Are Gay), that is when you can truly know that he is gay. The clearest way to know if your husband is gay is if he tells you. If a husband is gay, it can devastate not only the relationship but the straight wife as well. Sometimes a woman may have been in a heterosexual relationship for years and yet feel something is somehow "off " and she may find herself asking, "Is my husband gay?" Many women find this question unthinkable but according to Bonnie Kaye, M.ED., an expert in women married to gay men, it is estimated that 4 million women have been, or are, married to gay men.