For some years, I have had a relationship with a lovely man in Eastbourne, who is much older than me. But lately, he hasn't been able to "perform" because he has been feeling poorly. He has lost weight and is extraordinarily thirsty. Should I try and get him some Viagra?

Never mind Viagra for the moment. This poor chap almost certainly has diabetes. The combination of potency problems, weight loss and excessive thirst strongly suggests this disorder. Please get him to go to his doctor tomorrow, taking along a specimen of urine to be tested for sugar.