* Confession: The speaker is directly expressing their strong feelings of admiration and love to the recipient. This is a clear confession of their emotions.
* Enjambment: The lines "In vain I have struggled / It will not do" use enjambment, where the thought continues from one line to the next without punctuation. This creates a sense of urgency and a feeling of being overwhelmed by emotions.
* Metaphor: "My feelings be repressed" is a metaphor, implying that the speaker is struggling to contain their feelings, as if they are a physical force that is trying to break free.
* Imperative Sentence: "You must allow me to tell you..." is an imperative sentence, which is a command or request. The speaker is demanding the recipient to listen to their feelings.
* Hyperbole: "ardently admire and love you" uses hyperbole, an exaggeration, to emphasize the strength of the speaker's emotions.
While these are the prominent literary terms, you could also argue for other terms like apostrophe (direct address to the recipient), parallelism (repetition of the phrase "you must allow me") or assonance (repetition of the vowel sound 'o' in "allow" and "love").
Ultimately, the specific literary terms you choose to identify depend on your specific focus and what you want to highlight in the analysis of the excerpt.