What's the poem's tone up until the last line?"Richard Cory" by Edward Arlington Robinson

In Edward Arlington Robinson's poem "Richard Cory," the tone of the poem is both admiring in the first and second stanzas:  The speaker describes how perfect Richard Cory seems as he is a "gentleman" who is "Clean favored and imperially slim."  Yet, he was "human"--not pretentious--when he talked.

In the third stanza, the admiring tone continues, but it has an edge of envy:

In fine we thought that he was everything

To make us wish that we were in his place.

Even the first two lines of the fourth stanza indicate this envy, an envy which would naturally come as the poem recalls the 1893 economic depression when many a person suffered from malnutrition and want:

So on we worked, and waited for the light,

And went without the meat, and cursed the bread;

Then, the poem's tone changes to one of impersonal reporting followed in the last line with a rather bemused shock:

And, Richard Cory, one calm summer night,

Went home and put a bullet through his head.

This impersonal tone and rather distant admiring and envy do not prepare the reader for the final line, which is, indeed, shocking.