He's at the end of his life, an old man daydreaming on his deathbed, trying to come to terms with the guilt of how he abandoned a faithful woman that loved him.

He dearly wants to reconcile with her, to apologise, for her to relieve the burden of guilt, hence the scene were he beds with her again after years.

Then he remembers the truth, that his guilt will never be relieved, he left his loving wife to die, and now he cannot die peacefully knowing this, hence he started turning all old.