Is it obligatory to expiate an oath for a man to marry the wide-eyed houris in Paradise, after he swore to his wife in this world, "By Allah, by Allah, I will not marry anyone other than you"?

You are not required to expiate for your oath because it is specific to the women of this world. What matters in determining the oath is what you intended. If there was no intention, then what matters is the reason for the oath. The reason for the oath here is your wife's jealousy of you marrying another, and houris never crossed either of your minds.