'half broken-hearted to sever for years' conveys how a part of byron has been lost or irreparably damaged and the term sever evokes a sense of violence and emphasises the emotional trauma caused by their separation.
'pale grew thy cheek and cold'fading love is indicated through symbols of death which act as a metaphor for her dying emotions. he realises the downfall of their relationship was foreshadowed by his partners behaviour towards him. harsh C sounds allude to his bitterness.
'knell in mine ear' sombre ringing of a bell during a funeral service. memory of relationship causes him to reminisce about their painful break-up.
'in silence and tears' repeated at start and end to demonstrate the long lasting effects this will have on him. Also, the juxtaposition may show confusion over the situation.