Wondering what went wrong, need some opinions

[Annarose15]

Get a necropsy done ASAP.
Your QT period was too short even if you isolated him properly.

And since you exposed your female to him, I would definitely try to find out what happened to the male.

^ This. Anything else you are told on this thread is either sympathy (which is kind, but doesn't answer the question), or guesses. Pay for a necropsy, and then do some more research to find a vet that actually knows snakes before you need one again.