While taking Satsu out on an assignment to destroy a nest of vampires, Buffy reveals that she knew about Satsu's feelings for her; she warns Satsu from pursuing a relationship with her as her past romances ended in death.
She knew about Satsu's feelings for her. This is what Buffy reveals. She warns Satsu from. She was pursuing a relationship with her as her past romances. These past romances were ended in death.