Cayde was the first sentient being Failsafe met since being marooned on Nessus. Check in on her to see how she's processing his death.
The AI of the Exodus Black was not designed to experience complex emotions. However, centuries of isolation and self-repair turned a relatively simple program into a complex neural web. In a way, Failsafe's grief, simply because it exists, is beautiful.
It just doesn't feel that way to Failsafe.