The most obvious way in which this poem refers to the idea of waiting is with the refrain, which forms the final four lines of each stanza. In the first stanza, the refrain runs as follows:
She only said, 'My life is dreary,
He cometh not,' she said;
She said, 'I am aweary, aweary,
I would that I were dead!' (9-12)
This refrain - particularly the second line - emphasises the idea repeatedly throughout the poem that the title character, Mariana, is waiting for someone, who never comes. Who this person actually is, and where he is, we are not told. We can guess, however, that it is her lover who for whatever reason has deserted her.
The inspiration for the poem comes from the character Mariana in Shakespeare's play Measure for Measure, who was jilted by her fiance Angelo. Unlike Shakespeare's Mariana, however, Tennyson's character seems fated never to see her lover again; instead she spends her days and nights in futile longing.
Mariana's slow decay is reflected in her surroundings; the house in which she lives in a sad state of neglect, as vividly described in the openiing stanza. She has been left alone with merely stillness and the sounds of nature which are amplified by her feverish imagination:
The blue fly sung in the pane; the mouse
Behind the mouldering wainscot shriek'd (63-64)
The reference to 'the slow clock ticking' (74) reinforces the sense of the passage of time; it is gradual but relentless, and essentially, nothing happens - certainly not the change that Mariana is longing for. All she does is weep and wait.
The final stanza changes somewhat in effect, when the second line of the refrain becomes
'He will not come,' she said (82)
Here, at last, Mariana openly acknowledges that there is no hope at all for the future, that her lover will never arrive and rescue her from her isolation and desolation. For the first time, though, she also invokes 'God' (84) as though calling on a higher power to finally strike her down and put an end to her life of useless waiting once and for all.