He was such a stunning bun, cutting quite the dash
He seemed to know he was utterly gorgeous & struck so many handsome poses.
We had a similar situation with our two cats last year. They were the great love of each others life & then Floyd died suddenly & tragically.
Bailey was beside himself, as were we but it seemed doubly bad as every time we looked at him on his own he seemed so old, fragile & lost.
Eventually I found him a friend as he was still very lost & now about 8 months after we lost Floyd he is enjoying life with Lulu.
Granted it's not quite the same but he closer to our old Bailey.
Perhaps given some time you will get some of Lady Lydia back.