It’s all about confidence. In a marraige, I believe you need to set boundaries. One of them for me, applicable to both wife and husband, is that one shouldn’t expend emotional energy on a member of the opposite sex who isn’t related. At that point, one needs to think what is more important - a lifelong friendship with a member of the opposite sex or your husband/wife? I’m not talking about facebook friends or friend of the opposite sex that you see in a group setting etc. - I’m talking genuine hour long phone calls and regular one on one meet ups. Before things can get physical, they must first get emotional. Emotional attachment leads on to physical attachment.