Let me not to the marriage of true minds
Admit impediments. Love is not love
Which alters when it alteration finds,
Or bends with the remover to remove:
O no! it is an ever-fixèd mark
That looks on tempests and is never shaken;
It is the star to every wandering bark,
Whose worth's unknown, although his height be taken.
Love's not Time's fool, though rosy lips and cheeks
Love is able to view or ‘look on’ ‘tempests’ — that is, life’s storms and troubles — and remain unshaken. This reflects accurately the emotional state of being in love, when a couple is absorbed in the relationship, and detached from the outside world. This can continue throughout life, where both parties have to engage in the world, but the loving relationship is like a protective cocoon to which they can retreat. 
 Note the extended seafaring  metaphor , with the  lexical field  of sailing-related words; ‘tempests’, ‘star’(by which ships were steered) and ‘bark’ (a type of boat). 
 Note also how tempests sounds like  temptress , which could suggest that a temptress’s (or tempter’s) seductive look cannot tear two lovers apart.
Sonnet 116