Don't feel ugly!
It sounds like you are a wonderful and caring lover! don't feel ugly at all, a person caring for her lover as you are is beautiful! many things can cause impotence
, none of which involves you.
The development of impotence in a man in his 40's can be caused by minor problems, but also by serious disease, for example cardiovascular disease or diabetes
. He should really be evaluated by his doctor.
Answer assisted by Mike Moore, Medical Student