Question

what is the theme of if thou must love me?

Answer 1

Temporary love VS permanent love: For Barrett Browning, love can be of two types – one that lasts a little time, and one that lasts for all eternity. The love that is temporary is based on the particular – the particular way in which a person smiles, the particular look of a person, the particular way in which he or she thinks, et cetera. This kind of love is trivial in comparison to the other kind. The other kind is based on the universal – the universal emotion that we call love itself.
Hope it helps xd