The thing is that Gertrude is someone who is very self-contained out of necessity and is therefore only fortified against the Lonely insofar as she is even more so bloody-minded and stubborn and sure of who she herself is. Don't get lonely, get even.

She misses her cat and she does actually miss all her assistants, regardless of the fact that she would never admit it. She misses Adelard Dekker, and her relationship with Gerry, and she is more than keenly aware that a lot of the connections she doesn't have anymore are the result of her conscious choices.