The phrase cupboard love denotes love or affection insincerely professed or displayed as a means of gaining a benefit or advantage.

The image is of love given in return for food from a cupboard.

This phrase occurs, for example, in The Love Language of Butter, by Yotam Ottolenghi, published in The New York Times (New York City, New York, USA) of Friday 12^th February 2021:

Cupboard love is not always held up as a very pure form of love. At its heart is the relationship between the feeder and the fed. It is, in short, why your dog appears to love you and only you. It’s not, sadly, that your pet is the only one who truly understand your soul, but simply the fact that you fill its bowl with food once a day.

The English naturalist and theologian John Ray (1627-1705) recorded the synonymous phrase cream-pot love in A Collection of English Proverbs Digested into a convenient Method for the speedy finding any one upon occasion; with Short Annotations. Whereunto are added Local Proverbs with their Explications, Old Proverbial Rhythmes, Less known or Exotick Proverbial Sentences, and Scottish Proverbs (Cambridge: Printed by John Hayes, Printer to the University, for W. Morden, 1678):

Cream-pot love.
Such as young fellows pretend to dairy-maids, to get cream and other good things of them.

The earliest occurrences of the phrase cupboard love that I have found are as follows, in chronological order:

1-: From The Milkmaid’s Resolution (circa 1665)—as published in The Roxburghe Ballads (Hertford: Printed for the Ballad Society, by Stephen Austin and Sons, 1888), edited by Joseph Woodfall Ebsworth (1824-1908):

Some men they [make] love for what they can get,
And ’tis certain there’s many a Lubbard;
Will sigh and will pant, seeming ready to faint,
And all for the love of the cubbard, brave boys!
And all [for the love of the Cup-board].

2-: From The Proceedings at the New Bayley, in Weaver’s Square. Containing, Trials for Treason, Misprision, and all Crimes and Misdemeanors against the State and Peace of the Realm. Number I. Containing, The Trial of Jack of the Strand, alias Count Liffey. Published, By Order of the Commissioners (Dublin: Printed for Thomas Shuttle, 1756):

There is a Kind of Love in the Old Stile, termed Cupboard Love; and it often happens, that what People judge to be an Intrigue with a young Woman, turns out, on a nearer View, to be only an Intrigue with a Leg of Mutton and Turnips. This Kind of Love is frequently seen among certain Gentlemen at Country Quarters, the Curates in City Parishes, Attornies Clerks, and young Barristers, and may, doubtless, descend to all Degrees of Persons who have larger Stomachs than Purses.

3-: From Travels of the Jesuits, into various Parts of the World: Particularly China and the East-Indies (London: Printed for T. Piety, 1762), by John Lockman:

An Author, inserted in the religious Customs and Ceremonies of all Nations, illustrated with Figures by Picard, Vol. III. pag. 271, London, 1731, fol. observes, “that the lowest Christians or Parias, are held in the utmost Contempt by the rest of the Indians, who know very well, that most of those who embrace Christianity, are a Sett of beggarly Creatures; for which Reason they call them Christianos d’Aros, or Rice Christians, thereby intimating, that the sole Motive why they change their Religion is, to procure themselves the Necessaries of Life with greater Ease, and to be sure of some Rice to eat, there being no Bread in this Country”. If this be true, the Zeal of these Converts may be resolved into that vulgar Expression, Cupboard-Love.

4-: From Remarkable News from the Stars: Or, An Ephemeris for 1770 (London: Printed for the Company of Stationers, 1770), by William Andrews, Student in Astrology:

A Cupboard Love is seldom true,
A Love sincere is found in few:
But, ’tis high time for Folks to marry,
When Women woo, lest things miscarry.

5-: From The Westminster Magazine; Or, The Pantheon of Taste (London, England) of November 1773:

A PALINODE.

By a Gentleman who had offended a Young Huswife [sic], by rallying her on the Scarcity of Butter at her Table.
Once in a dairy, a malignant Lout,
Whose love was Cupboard Love, star’d round about,
And ask’d my Kitty, in a hungry mood,
Why Butter now was grown so scarce a food?
Unknowing Carle! for Cream is always dear,
In ev’ry climate where the sun is near;
And Kitty’s eyes do with such lustre shine,
They curdle Milk, but help the generous Vine.

6-: From A Classical Dictionary of the Vulgar Tongue (London: S. Hooper, 1785), by the English antiquary and lexicographer Francis Grose (1731-1791):

Cupboard love, pretended love to the cook, or any other person, for the sake of a meal.

7-: From The Young Men and Maids Delight; Or, The New English Valentine Writer; Containing a Variety of Verses calculated to crown with Mirth and good Humour, the happy Day which is called St. Valentine (London: Printed and sold by T. Sabine, [1787]):

WILL the Coachman, to JENNY the Cook.

Jenny, when’er you roast or boil,
You make my heart within me broil;
Or when you’re at those pleasing arts,
Of making puddings, pies, or tarts;
I lick my lips at such good cheer,
And call you then my life and dear;
What tho’ with grease, your garments shine,
Yet you must be my Valentine.

ANSWER,

Go mind your horses in the stable,
You ne’er shall sit with me at table;
For your own words do plainly prove,
You’ve nothing more than cupboard love.
So beg you will your suit decline,
You shall not be my Valentine.