Q. A 65-year-old man has had worsening erectile function for one year. He is now avoiding sexual intimacy. His wife is very concerned and asks him to see his GP. The GP tells him not to worry as it is a normal part of the ageing process. After a further 6 months, as the situation gets worse, the patient goes to see another partner in the practice who refers him to the urologist. How would you define erectile dysfunction?