Tim Tam said...
What if he died, and you regretted not spending more time with him because you were retaliating because he had not spent more time with you and your wife?
Then you would regret not spending more time with him, it goes in a circle.
"If equal affection cannot be, let the more loving one be me." What can't you be the more loving one?
Or, "Love is like a magic penny. Keep it and you won't have any. Lend it, spend it, give it away, and it will come back to you one day."
Maybe you'll gain by helping him. What does you wife want to do? If she wants to see her father, then maybe that's the important thing, also.
"Of each other, we should be kind
While there is still time."