After a good dinner one can forgive anybody, even one's own relations.

Wilde treats forgiveness less as a lofty moral achievement than as a mood contingent on bodily satisfaction and social ease. The “good dinner” stands for comfort, pleasure, and the civilizing veneer of hospitality: when one is well-fed, irritations recede and generosity becomes effortless. The sting is in “even one’s own relations,” implying that family—supposedly the natural object of affection—can be the hardest to tolerate. As with many Wildean epigrams, the line reverses expectations: it suggests that virtue may be a byproduct of circumstance rather than character, and it gently mocks the way society confuses good manners (or good digestion) with genuine moral feeling.