Answer:
The speaker uses this line to express how far his loved one is from him.
Explanation:
"To his coy mistress" is a love poem, where the speaker reinforces the idea that the time he and the woman he loves have to be together is very little and passes very quickly. For this reason, they should enjoy as much as they can, to love each other and get together as quickly as possible, but this will only be possible if his loved one stops being shy. At the beginning of the poem, he says he wouldn't complain about anything if they had all the time in the world to live this love, but they don't and are wasting that time creating a distance between them, as if she were on the side of the Ganges River, in India, and he was on the side of the River Humber, in England.
