How we cite our quotes: line
Quote #1
But we looked into a fire, we leaned across a table,
We lay on a hill-top underneath the moon;
And the whistles kept blowing, and the dawn came soon. (3-6)
The speaker emphasizes the "we"-ness of the actions she remembers, making sure that the reader knows that everything that happened that night was done with "you."
Quote #2
We had gone back and forth all night on the ferry;
And you ate an apple, and I ate a pear, (8-9)
The syntax of line 9 feeds into the sense of shared actions set out in lines 7 and 8: the repetition of "and" allows the speaker to describe each individual's actions as if they were part of a related whole.
Quote #3
We hailed, "Good morrow, mother!" to a shawl-covered head, (15)
The casual use of "mother" here signals a sort of kinship and respect which is actually more like friendship than actual family relations.
Quote #4
And she wept, "God bless you!" for the apples and pears, (17)
Does generosity (and the blessing which it inspires) signal a sort of bond between the speaker and the old woman? And if so, what sort of bond is it? It's difficult to tell, since the poem is deliberately short on emotional reflection.