Who is the Beloved in Donne's poem, The Flea?

The Beloved is a woman whom the speaker is trying to seduce. While she does not speak, the speaker addresses her throughout the poem and describes her actions such as killing the flea. The lady is concerned with her honor and preserving her virginity, and thus rejects the speaker's advances for sex before marriage. At the end of the poem, she triumphantly tells the speaker that she feels no weaker after killing the flea and his argument about them both being alive inside the flea is invalid. The speaker uses the occasion to turn her argument against her and assert that if she feels no weaker, swapping bodily fluids will be no disgrace to her honor.