Brooke is actually struggling with a real psychological phenomenon and people are screeching ree about it? Why? It's a real thing people go through. It's called insecurity.
Frances lack of concern about Brooke creates a situation where she has to worry how much he actually needs her, and if he doesn't need her, it creates a concern that he wont produce if needed.
I even find it to be pretty realistic because her relationships prior to this had been sex focused, fuck buddies, kink.
I lost my virginity in a NSA internet fuckbuddy situation. Every relationship since was friends with benefits, which turned into relationships later. The insecurity that creates is pretty real because the physical act of sex no longer amounts to a declaration of deep affection or want.