He sees this as a transactional situation, and he will get nasty the moment he feels he won't get the returns on his "investment".

I mean that's possible... But no, it's not certain at all.

My girlfriend has rich parents, she's the type to do this kind of stuff, and we've been together for 5 years. She's also a communist and a class traitor. She sees generosity as fairness: if her family has a lot and her friends have little, she's got more of a responsibility to provide for all of us than we do. Also, she's never worked a paying job in her life and has no clue about the actual value of money. She's willing to give away money because it's just not that valuable to her.