Nothing in the first four stanzas of Raleigh's poem says "I". Love is addressed, accused and called names, but the man doing the shouting stays out of sight until the fifth stanza, when "my younger years" suddenly appear and the tirade turns into a confession. That delayed entrance is the poem's cleverest move. It shows that the subject is not love in general but the speaker's embarrassment at having been taken in by it.
The central idea is that love is a fraud, a thing that looks like one thing and is another. The poem's images keep returning to surfaces that hide danger. Love is "a poisoned serpent covered all with flowers" and "a gilded hook that holds a poisoned bait". Both pictures show something attractive with harm underneath. Other images belong to traps and hunting: a "net of deep deceit", a "maze wherein affection finds no end", and, in the last stanza, "trains", which here means snares. Elsewhere love is a "siren song", a "fever of the mind" and a "quenchless fire". Each image makes the victim passive, someone caught, lured or burned.
The structure supports this. Each of the five stanzas has six lines of steady iambic pentameter, rhymed ababcc, and each ends in a tight couplet that closes like a lid. Some of those rhymes are pointed. In the first stanza "treason" is paired with "reason", so the word for love's betrayal sits right beside the faculty it betrays. Reason is the poem's measuring stick throughout. Love is "contrary unto reason" in the first stanza, then "a fortress foiled, which reason did defend", then "a hope of that which reason doubtful deems". The line "a goal of grief for which the wisest run" admits that the wisest are caught too, which makes the speaker's lapse easier to forgive.
The most striking technique is the catalogue. After the opening "Farewell", the verbs almost vanish, and what follows is a stream of labels, each starting "A" or "An": "an envious boy", "a bastard vile", "a school of guile". The effect is relentless, like a man who cannot stop listing grievances. The "boy" who appears twice, first "envious" and later "idle… in pleasure's lap", recalls Cupid. Raleigh makes him spiteful and then lazy, as if love were cruel one moment and careless the next.
By the fourth stanza the language itself begins to wobble. Love is "a substance like the shadow of the sun", which is nearly a contradiction, since shadows have no substance. It is also "a deep mistrust of that which certain seems" and "a true retreat of sorrow and despair", where "retreat" ought to suggest shelter. The poem's own phrases become unreliable, as love is claimed to be.
The final stanza changes the sound. Archaic words such as "sith" (since), "bewrayed" (exposed) and "kind" (nature) give it a legal, almost penitent tone. The speaker blames himself as well: "repentance hath my wrongs bewrayed". Then the metaphors change. The serpents, hooks and fires give way to a plant, and the last line is plain: "Dead is the root whence all these fancies grew." The flowers that disguised the serpent in stanza two come back here as something with a root, so the poem ends by suggesting that the whole tangle of "fancies" grew from one source. Putting "Dead" first makes the line sound like a verdict.
Whether the verdict is believable is open to question. A speaker who has really finished with love would hardly need some twenty accusations to say so. The energy of the insults hints, in my reading, that the feeling is not as dead as the final line claims, or at least that it took a great deal of effort to kill.
That tension is what makes the poem worth reading. Instead of praising love in the usual way, it borrows love's attractive vocabulary of gold, flowers and music and shows the hook inside each one. It is also unusually honest about the speaker's own part in the deception.