No way would I criticise a 55 year old woman for having a 55 year old body, thats just a whole truck load of wrong, nor would I feel I was doing her a favour in telling her how to project her body for my own sexual arousal benefit, massive privilege going on there IMO.
But some of the replies here miss the mark to me. 'Service his sexual desires' assumes she actually could; as well as assuming he still had them. Sexual desire is a funny thing but its not a car, it cant be serviced by a mechanic no matter how qualified they are or think they are. Sexual desire is the attitude of the driver of the car, not the car itself.
As to 'erectile dysfunction' grimbletart, sure- its quite possible but I have problems with your view. Getting an erection is not as simple as just wanting it to happen, you have to want it with the reasons that make it happen. Failure to achieve an erection does not make it a dysfunction unless you cant reliably get an erection in other circumstances. If he gets wood over 20 year old women in nurses uniforms or he is a dendrophile and gets wood over wood, or be what may, that is his sexuality to deal with.
But by invoking the 'erectile dysfunction' card you assume his sexual desire for her was actually there after she took her clothes off. I find that a huge assumption, one not born out by the authors commentary. In some ways its almost a get out of jail free card for the authors desirability in the eyes of oithers, you could re-write is as: 'he desired her but was unable to actualise that desire- thus in his bitterness he wounded her with his words'. Maybe so but maybe not. If he did not desire her sexually then he did not desire her sexually. Failing to express what he felt in a more mature and positive way, one that would be less of an assault on her sense of self esteem, that is his fault. Failing to desire her is not.