"On Her Loving Two Equally" by Aphra Behn is a humorous poem describing the situation of a narrator who rather likes having multiple admirers. This isn't a poem about a deep, serious romance, but rather about a narrator who likes flirting and attention and really doesn't want to give up either Alexis or Damon.
One of the ways we know that this poem is meant as lighthearted is that the narrator says that when she is in the company of Damon, she thinks of Alexis and:
When my Alexis present is,
Then I for Damon sigh and mourn;
In other words, she is really not deeply in love with either of the two men, but enjoys being courted by both of them. The final stanza emphasizes that she really doesn't want a deeper relationship with just one of the two, but rather she just enjoys playing them off against each other. This is why the title is "On Her Loving Two Equally"; neither of the two is favored over the other.