I never said I loved you, John:
Why will you tease me, day by day,
And wax a weariness to think upon
With always "do" and "pray"?
The speaker begins abruptly with a clear statement from which she doesn’t deviate throughout. Her emphatic rejection establishes the character of the young woman; assertive and uncompromising. 
 Rossetti’s use of language is interesting; there is a forceful removal of the “male voice”. Rossetti allows only her own voice to be the sound of the poem,  reinforcing this sense of female empowerment.
No thank you John