Sweet love, renew thy force; be it not said
Thy edge should blunter be than appetite,
Which but to-day by feeding is allayed,
To-morrow sharpened in his former might:
So, love, be thou, although to-day thou fill
Thy hungry eyes, even till they wink with fulness,
To-morrow see again, and do not kill
The spirit of love, with a perpetual dulness.
Let this sad interim like the ocean be
Which parts the shore, where two contracted new
Come daily to the banks, that when they see
Return of love, more blest may be the view;
As call it winter, which being full of care,
Makes summer's welcome, thrice more wished, more rare.
Another  metaphor  for the absence of love – the frost and cold of winter. “Care” in this instance means “anxiety” or even “hardship”. Winter in Shakespeare’s time was for many the season of starvation and death. 

Sonnet 56