I've had the long hair for 6 years and recently adopted the short hair (2023). This is the closest they have been to each other since. So much for getting another cat for companionship. I do work with them to try and build a relationship, but cats will be cats.
We adopted 2 brothers and they never sleep together like this. One of em has urinary issues and the doctor insists it might be stress related and that we should consider getting rid of 1 of the 2 :(
I would suggest a second opinion, if feasible. Also, I bought a couple of the "calming diffusers" with pheromones, etc. It isn't a fix, but I figured it can't hurt. Also, for working with them... They do enjoy my company. When they both come to me looking for scratches, I grab a couple "calming treats" to give them, in hopes that they get a positive reaction when they are together. Maybe see if that helps. I hope they get better!