He often gets emotional and gets extremely horny since his son married a beautiful and extremely delicious young wife.
He longs to fuck his daughter-in-law. once and that was enough for him to feel satisfied for the rest of his life.
He often secretly peeked at his daughter-in-law while bathing. Every time he did, his cock would get "tense" and he just wanted to rush in. fucking his son's beautiful young woman to death.
And he was lucky to know that his daughter-in-law was also extremely lustful, and also liked sex...