I only get sexually aroused while with my wife and fail to if I try to sleep with another woman. Why?
An erection is the hardening of the penis due to an increased inflow with a restricted outflow of blood into the penis. An erection can happen by reflex (erections resulting from actual contact), psychogenic (erections resulting from a fantasy), and nocturnal (erections that occur during the dreamy part of sleep). Much as they can be complex, erections involve the brain, hormones, emotions, nerves, muscles and blood vessels.
Erecting with your wife and not with any other woman much as it may seem bizarre may have nothing to do with charms but the brain holding 80 per cent of sexual performance, being selective about who to offer a sex service to and who not to. The selectivity among others is guided by psychological, cultural, religious, ethical and emotional factors.
Negative emotions such as fear, guilt, and prejudice can make you fail to erect with other women. Fear to sin if you are religious or to contract STIs and HIV, guilt of cheating, or tribal prejudices may also cause the selectivity. Many times, when one is newlywed, has a new girlfriend or has an infatuation, he may fail to erect with other women while erecting with the wife or girlfriend only. So, what is happening to you is normal and good for your marriage.