The poem deals mostly with love.

."..when you can no more hold me by the hand..."

Here she is telling her lover to try and let go of her and the memories that he holds of her.

."..nor I half turn to go yet turning stay..."

Rossetti is saying here that when her time comes, she is going to have to go. She will be unable to avoid her death, and she will take it as it comes.

."..only remember me; you understand

It will be late to counsel then or pray..."

She is saying here that her lover should only remember her. He shouldn't pray or cry for her, as it isn't going to bring her back.

."..if you should forget me for a while

And afterwards remember, do not grieve..."

Here, Rossetti is telling him that he shouldn't feel guilty for not grieving for her, or forgetting about her. She wants him to carry on without her.

."..vestige of the thoughts I once had..."

Rossetti is telling her lover to remember her for the things she did and they did together, rather than the things that she didn't do, or the things they didn't do together.

."..better by far you should forget and smile

Than that you should remember and be sad..."

Here, Christina Rossetti is telling her lover that she would rather he moved on without her, forgot about her and was happy, than spending his whole life grieving for her and being miserable.