Love is more pleasant than marriage for the same reason that novels are more amusing than history.

[L’amour plaît plus que le mariage, par la raison que les romans sont plus amusants que l’histoire.]

Nicolas Chamfort (1741-1794) French writer, epigrammist (b. Nicolas-Sébastien Roch)

Products of Perfected Civilization [Produits de la Civilisation Perfectionée], Part 1 “Maxims and Thoughts [Maximes et Pensées],” ch. 6, ¶ 391 (1795) [tr. Merwin (1969)]
    (Source)

(Source (French)). Alternate translations:

Love gives greater pleasure than marriage for the same reason that romances are more amusing than history.
[tr. Hutchinson (1902), "The Cynic's Breviary"]

Love is a pleasanter thing than marriage, for the same reason that the Romans are more amusing than History.
[tr. Mathers (1926)]

Love is more pleasant than marriage for the same reason that novels are more pleasant than history.
[Source]