Hi there...erectile dysfunction could be due to many reasons. Anxiety being the most. So first let him try relaxation techniques and distraction method. Then try to cut down on any habits like alcohol, smoking or drugs. This will help. If there's no improvement then he must be investigated for any comorbidities like diabetes hypertension hypercholestrolemia. Treating these comorbidities also help. Medically there are many options like oral medications and topical creams. If the above conservative measure do not help kindly consult a psychiatrist for medical therapy.