This passage is an excellent example of the literary device parallelism. Parallelism is created when an author repeats certain elements, such as words, structure, or grammatical elements, to create an effect.
One form of parallelism we see in this passage is isocolon parallelism in which a parallel is formed from two sentences or clauses. We especially see isocolon parallelism in the line, "O brawling love, O loving hate" (174). First, both clauses are constructed of three words, which is one parallelism, but the sentence structure of interjection + verb + noun is also paralleled in both clauses. The interjection "O" is used in both clauses, and thus paralleled. The verb "brawling", meaning "to fight" is paralleled with the verb "loving," meaning "to feel affection." In addition, the noun "love" is paralleled with the noun "hate." Hence, since both clauses are perfectly paralleled, we see that this is an example of isocolon parallelism.
However, this line is also an excellent example of antimetabole parallelism in which the order of repetition is reversed, as in the line, "Fair is foul and foul is fair" ("Schemes," Dr. Wheeler). The noun "love" at the end of the first clause switches places and becomes the verb "loving' in the second clause. Likewise, the verb "hating" in the first becomes the noun "hate" at the end of the second, creating a perfect reversal of parallel ideas.
Another example of antimetabole parallelism can be found in the line, "This love feel I, that feel no love in this." In this line, the pronoun "this" is the subject of the first clause and then becomes the object of the second clause, showing us reverse order. Also, the word order of "love" and "feel" is reversed in the second clause.