The Question and Answer section for Christina Rossetti: Poems is a great resource to ask questions, find answers, and discuss the novel.
From what I can gather, this is a playful love poem towards a man the speaker is interested in.
The poem revels in the new sights of spring after a long winter. The poem is about light and rebirth and the promise of rejuvenation amongst nature’s coming back to life.
On one hand, the speaker does not want her lover to forget her but then says that he should because it is better to "forget and smile" than to "remember and be sad."