Can anyone please give the theme and an analysis for this Poem ?

It sounds definitely like a woman wrote it. The attention it gives to desire as not her own, but from someone else for her, which is the vanity of all vanities, is just a woman's concern about losing her beauty. Women's love is a response to a man's love or desire, so when it talks about her heart, it really means the love of a man or men that is no more because the woman has become old.