As for the duties of marital love that some people consider injured by absence, I do not believe it. On the contrary, it is a relationship that is readily cooled by too continual association, and harmed by assiduity. Every strange woman seems to us an attractive woman. And every man feels by experience that seeing one another continually cannot match the pleasure of parting and being together again at intervals.

[Quant aux devoirs de l’amitié maritale, qu’on pense estre interessez par cette absence: je ne le crois pas. Au rebours, c’est une intelligence, qui se refroidit volontiers par une trop continuelle assistance, & que l’assiduité blesse. Toute femme estrangere nous semble honneste femme: Et chacun sent par experience, que la continuation de se voir, ne peut representer le plaisir que lon sent à se desprendre, & reprendre à secousses.]

Michel de Montaigne (1533-1592) French essayist
Essays, Book 3, ch. 9 (3.9), “Of Vanity [De la vanité]” (1587) [tr. Frame (1943)]
    (Source)

First appeared in the second (1588) edition. See also Propertius (c. 20 BC), La Rochefoucauld (1665), Ouida (1878).

(Source (French)). Alternate translations:

Concerning dueties of wedlocke-friendship, which some happily imagine to be interressed or prejudiced by the husbands absence, I beleeve it not. Contrariwise, it is a kinde of intelligence, that easily growes colde by an over continuall assistance, and decayeth by assiduitie; for, to stand still at racke and manger breedeth a saciety. Every strange woman seemeth to us an honest woman: And all feele by experience, that a continuall seeing one another, can not possibly represent the pleasure, men take by parting and meeting againe.
[tr. Florio (1603)]

As to the Duties of Conjugal Friendship, that some think to be violated by the absence, I am quite of another Opinion; it is on the contrary an Intelligence that easily cools by a too frequent and assiduous Practice. Every strange Woman appears graceful, and every one finds by Experience, that being continually together is not so pleasing, as to part for a time, and meet again.
[tr. Cotton (1686)]

As to the duties of conjugal friendship, that some think to be impaired by these absences, I am quite of another opinion. It is, on the contrary, an intelligence that easily cools by a too frequent and assiduous companionship. Every strange woman appears charming, and we all find by experience that being continually together is not so pleasing as to part for a time and meet again.
[tr. Cotton/Hazlitt (1877)]

As for the duties of conjugal friendship, which are thought to be wronged by such absences, I do not believe so; on the contrary, it is an intercourse which easily grows cool with too continuous companionship and which assiduity injures. Every woman who is a strange seems to us a worthy woman; and we all know by experience that continually being together cannot equal the pleasure that we feel in parting and meeting by turns.
[tr. Ives (1925)]

As for the duties of conjugal love which are thought to be infringed by such absences, I do not believe that they are. On the contrary: such intercourse can easily be cooled by too continuous a presence and impaired by assiduity: every other woman seems charming then! Everyone knows that seeing each other all the time cannot provide the same pleasure as is given by alternately going away and coming together.
[tr. Screech (1987)]