For, what seems most pertinent for him to say, if he loved, "Take, O Fates, your promise back, and take my life, not hers," he does not say.

That is not really the thought of Euripides.
Then, and this is subtly but not quite justly wrought into Euripides by Balaustion, she traces through the play the slow awakening of the soul of Admetos to the low-hearted thing he had done.

He comes out of the house, having disposed all things duteously and fittingly round the dead, and Balaustion sees in his grave quietude that the truth is dawning on him; when suddenly Pheres, his father, who had refused to die for him, comes to lay his offering on the bier.

This, Balaustion thinks, plucks Admetos back out of unselfish thought into that lower atmosphere in which he only sees his own advantage in the death of Alkestis; and in which he now bitterly reproaches his father because he did not die to save Alkestis.

And the reproach is the more bitter because--and this Balaustion, with her subtle morality, suggests--an undernote of conscience causes him to see his own baser self, now prominent in his acceptance of Alkestis' sacrifice, finished and hardened in the temper of his father--young Admetos in old Pheres.