The prenup Lars helped arrange for Uncle Nils, was more properly done and more complete than Carla Dewberry's.
Premarital agreements are commonly viewed as tools of deprivation and exploitation. Prenups are perhaps most common in later-in-life marriages, and the parties are likely to differ in wealth. Does the rich old guy secure the younger and poorer woman at a bargain, leaving her with little after she looks after him for years? Sometimes. But an agreement can be a useful form of communication, resolving important practical questions that might otherwise go unasked. Is Sylvia promised any financial reward? How much, and in what scenarios?
The answers aren't always miserly. Many lawyers recommend a degree of generosity. This is partly because a stingy arrangement is more likely to be found invalid in a later divorce. But there's also the factor that it's a marriage being talked about, not a sale of property between unrelated persons. Nils has no kids and has plenty of money. Why not make a nice gesture to the woman he's marrying?
Nils and Sylvia's document was drafted by his attorney, then reviewed by hers with her. It was done months in advance of the wedding, as a last-minute deal is breakable, implying the possibility of duress. His separate property remains that way. But she gets the house and a $2 million trust out of it if they divorce after at least three years, or if Nils dies before her.
This is what Nils has agreed at the outset, that he must do for Sylvia in those events. He might be a little worried she is more interested in his money than in him, although she does seem genuine. If things go well he can be even more generous; their agreement certainly doesn't prevent that.
Surprising things happen sometimes, with women and men...