Sadly it does take time.
I think Our Cats are closer to each other than a lot of people, even family as Our Cats dont have the baggage that we have with other people.
They love more unconditionally , and more deeply.
I know My Juke Joint Joseph misses His John Hnacock a great deal.
Maybe one day you will see a Cat who needs a home badly, and Sylvester will have a New Friend.
I think Bear would like that , and Bear would be thier Guardian Angel, the way My Found Cat Angels are here!
Thier Love is Furrever