Imagine you have a friend who has very generously offered to drive you to the airport in the morning. Your flight however is delayed and it turns out you really don't need that drive until the afternoon. When you inform your friend of this, he suggests you hire a taxi instead, since he was planning to take a nap after lunch.
I'm looking for a word or phrase that captures the contrast between someone's generosity and their inflexibility in how they are generous. I don't necessarily want to imply that these restrictions on their generosity are unreasonable, just surprising, given that generosity is so often paired with a desire to accommodate.
The archetypal example is probably parents who are willing to spend a fortune on a lavish wedding for their daughter, but make a stink when that daughter requests some small thing that they do not see as essential.