In speaking of joy, let’s be sure to distinguish between this quality and simple happiness. Joy strikes me as an Ignatian quality, something that will draw a person to a deeper fulfillment. Not just immediate gratification.
126. In marriage, the joy of love needs to be cultivated. When the search for pleasure becomes obsessive, it holds us in thrall and keeps us from experiencing other satisfactions. Joy, on the other hand, increases our pleasure and helps us find fulfilment in any number of things, even at those times of life when physical pleasure has ebbed. Saint Thomas Aquinas said that the word “joy” refers to an expansion of the heart.(Cf. Summa Theologiae I-II, q. 31, art. 3., ad 3) Marital joy can be experienced even amid sorrow; it involves accepting that marriage is an inevitable mixture of enjoyment and struggles, tensions and repose, pain and relief, satisfactions and longings, annoyances and pleasures, but always on the path of friendship, which inspires married couples to care for one another: “they help and serve each other”.(Gaudium et Spes 48)
A married person can struggle with her or his spouse, and yet still gaze on the partner and believe that in shared struggle and mutual service, they will persist on their chosen path.
Remember that Amoris Laetitia is online here.