Bo keeps his distance when Petal leads Didi out of the small room. Didi only notices because it's irritating, really, how he hangs off the outer edge of their lives like that, all droopy and sad, as if she's beaten him or mistreated his sorry excuse for a heart. She could be kinder, maybe, choose to offer some words of comfort or remorse, to take the blame she knows she shares and let him off the end of her pointed hook.
Instead, vindictiveness wins. She avoids him purposely and focuses on her mother.
Not that doing so is hard. From the instant Petal shows the way into the main corridor of her base, Didi feels the pressing power of her mother's presence. Not dominating or hurtful, without a trace of arrogance. Instead, Petal's very being seems to command respect and instant response, something Didi admires and secretly longs to emulate.