This poem is Dickinson interrogating divine indifference, written by someone who spent her life wrestling with Calvinist theology. The approving God in the final line is the key—this isn't a distant or neglectful deity, but one who actively endorses the casual violence of nature.
The poem's structure mirrors its argument. Everything proceeds in orderly fashion: frost kills, sun measures, God approves. The iambic meter is almost sing-song, which makes the violence more disturbing. There's no drama, no intervention, just mechanical process. The flower dies apparently with no surprise because in Dickinson's natural theology, this is how things work.
Notice the escalation of agents: frost (natural force) → sun (cosmic force) → God (divine force). Each is more powerful and more indifferent than the last. The sun proceeds unmoved—it doesn't even pause. It just keeps measuring off days like a bureaucrat with a ledger, all for an approving God who watches the whole system run.