Especially if he had previously had normal arousal and sexual relations. Unfortunately, at one time or another, almost all males have or will experience this problem, and thus, somewhat normal occurance. In about half or so of the documented cases of impotence, the cause is purely physical. Various medications can also contribute to the problem of impotence. Medications for hypertension and those that cause drowsiness, such as antihistamines, can be the cause.
Psychological problems are the cause of impotence in the other half of the cases.
Men who are stressed out from work or who are having problems at home in a relationship, or with the finances, can have problems with impotence. Failure to perform sexually, only adds great fuel to the fire, so to speak, because anxiety and fear of failure, will only enhance the difficulty of getting a maintaining an erection. Men who are seriously depressed will have diminished or no sexual desire. Pointing out the problem to a man, especially during sex, will only make the problem much worse. The main way to differentiate between a physical or psychological cause is this.