What argument does Aphra Behn make about her two loves in the passage: "How strongly does my passion flow, Divided equally 'twixt two? Damon had ne'er subdued my heart, Had not Alexis took his part; Nor could Alexis powerful provce, Without my Damon's aid, to gain my love."

Is it that she doesn't really love either of them or that each lover enhances the qualities of the other?

She says her passion is divided, and she says it is strong. She now loves them both. Read the rest of the poem.

Based on the passage you provided, Aphra Behn is making an argument that each lover enhances the qualities of the other. In the passage, she states, "Damon had ne'er subdued my heart, Had not Alexis took his part; Nor could Alexis powerful prove, Without my Damon's aid, to gain my love."

To understand this argument, it's important to analyze the lines closely. The lines suggest that Aphra Behn's passion is divided equally between two individuals, Damon and Alexis. She implies that her love for Damon was ignited or intensified because of Alexis's involvement, and likewise, her love for Alexis was made powerful with Damon's assistance. Therefore, she suggests that her affection for each lover is enhanced by the presence and influence of the other.

To arrive at this understanding, it is crucial to pay attention to the specific words and expressions used in the passage and interpret their context and meaning. In this case, the words "subdued," "took his part," "powerful prove," and "aid" all indicate collaboration and synergy between the two lovers, illustrating the argument that each lover enhances the qualities of the other.