Married life has never been much of a topic in European art, literature, or drama. Ever since Menander, comedy traditionally deals with a pair of lovers who have to overcome some obstacles to be allowed to marry, but the comedy is over as soon as these obstacles are overcome. Novels, too, tend to end with marriage rather than begin with it, this is true for romance novels as well as Picaresques like Tom Jones. A small subset of romance novels, of which The Scarlet Pimpernel is probably the most famous example, do deal with a married couple, but one that has not fallen in love yet, and again ends when this is achieved.
Likewise it has been uncommon for married couples to be portrayed on a single painting. Separate portraits in matching styles are found more often. And even if a painting shows a married couple, it rarely shows their relationship, their love. There is a famous self-portrait of Rembrandt holding his wife on his lap, but officially it’s an illustration of the Parable of the Prodigal Son. Western painting can be quite sensual (Boucher’s Heracles and Omphale especially comes to mind), but that’s mostly reserved for mythological themes.
So when Charles Auguste Émile Durand, who signed his pictures as Carolus-Duran, painted himself kissing his newlywed wife in 1868, he created a first.