“those know little of real love or grief who do not know how much we deceive ourselves when we pretend to aim at the cure of either.”
Booth recognizes that people may claim to be curing love or grief while unconsciously choosing actions that keep those feelings alive.
Source details
Amelia, Book II, Chapter III, “The narrative continued. More of the touchstone,” Project Gutenberg #6098, George Saintsbury edited witness. Captain Booth says the love / grief sentence while recounting his failed attempts to cure himself of attachment to Amelia. It is fictional retrospective speech, not clinical guidance about grief or relationships.