I take it as being about a lover that has "betrayed" you (although could be about an individual or entity too).
"You've made your promises, that I have drowned inside
The windswept shore is silent in absence of the tide"
These lines that are repeated suggest that they promised their loyalty / love to someone and fully believed in their relationship (gave it their all ... drowned their own self to be with them), but now that they have swept them aside they are not sure of who they are. That is, they are "lost" (absent of the tide) without them because they gave themselves so fully to that relationship.
I take it as being about a lover that has "betrayed" you (although could be about an individual or entity too).
"You've made your promises, that I have drowned inside The windswept shore is silent in absence of the tide"
These lines that are repeated suggest that they promised their loyalty / love to someone and fully believed in their relationship (gave it their all ... drowned their own self to be with them), but now that they have swept them aside they are not sure of who they are. That is, they are "lost" (absent of the tide) without them because they gave themselves so fully to that relationship.