The widower has already shown immense generosity by gifting his late wife's truck to her parents. He shouldn't be guilt-tripped into jeopardizing his financial stability and future with his fiancé. It's his house, and he has every right to sell it on his own terms. His in-laws are being unreasonable.
The man is clearly prioritizing his own convenience over the needs of his late wife's parents, who are already dealing with the emotional burden of downsizing. He's using the truck as an excuse to avoid helping them, conveniently forgetting the years of support they likely provided. He should consider the emotional impact of his decision on his in-laws.
While the widower has the right to sell his house as he sees fit, his in-laws' request isn't entirely unreasonable given their close relationship and his past generosity. However, the widower cannot be expected to shoulder a financial burden indefinitely. A compromise, such as a formal agreement with a reasonable deadline and financial safeguards, would have been a more considerate approach. His financial well-being is also important. He gave them a truck, they should find a way to figure it out.