For someone with her head decidedly out of the clouds, the nymph in "The Nymph's Reply" spends an awful lot of time hypothesizing about what her life would be like if "youth could last" (21) and "all the world and love were young" (1). Is her hypothetical world something she longs for in reality? Does she want to be down with this shepherd's pleas? Or do the hypotheticals only underscore the unobtainable realm described in "The Passionate Shepherd," reminding us that this poor shepherd has zero chance with her?
The speaker's hypothetical remarks do not reflect genuine investment in an unobtainable world. Nope, this nymph longs for simpler times and the chance to do things differently in her own past.
Come again?! The hypothetical conditions of the nymph's acceptance of the speaker's offer don't make sense. She speaks of a world where youth is eternal and joys have no date, but all the natural phenomena she mentions in the poem (decay of flowers, coming of winter, impermanence of material goods) have nothing to do with youth or happiness.