I'm not sure I'd call them 'key relationships' so much as a series of cages she has to pick the locks on. The first one is Nanny, who loves her but with a love so soaked in trauma and fear that it's the first brick in the wall. She marries Janie off to Logan Killicks for safety, not love, and that sets the whole thing in motion: Janie learns what a relationship isn't.
Then there's Joe Starks. Oh, Joe. He builds her a gilded cage, puts her on a pedestal to silence her. That's the relationship that teaches her about power and voice, or the lack of it. She realizes you can be both worshipped and completely unseen at the same time. His death isn't just a plot point; it's the sound of a lock clicking open.
Which brings us to Tea Cake. That's the messy, risky, real one. It's not idealized—he hits her, he gambles, he's far from perfect. But he also sees her, talks to her as a person, lets her be Janie. Their relationship is the horizon she was always looking toward. Even the rabies and the final, tragic shot... it's part of the same wild, painful, authentic journey. In the end, the most important relationship is the one she forges with herself, alone on that porch, having loved and lost and lived through it all.