Stanley will be just fine without your getting him a friend.
YOU are his friend and flockmate. They do just fine being a single bird as long as they get attention from their humans.
Besides, like illusive pointed out...there is never a guarantee that Stanley would even LIKE a new one of you got one. Sometimes they just plain do not get along.
AND you would need another cage to quarantine the new one.
Just be patient. Stanley will come around and be just fine. Work with him slowly EVERY day, build up his trust in you. You'll see that if you take the time and be patient..working at HIS pace, never forcing yourself upon him, he will be a very happy and well adjusted little bird.
gain, sorry for your loss. I did see in your other thread what happened to Rhonda..so disregard what I said about the one you lost maybe having been contagious.