There's another way to edit the sentence, which is to add a...

There's another way to edit the sentence, which is to add a comma before the second 'which.' The survivor is struggling toward 'some resolution,' not a specific resolution that the mind may never find. The final clause is an appended thought, not a conclusion of the previous clause: 'Death ends a life, but it does not end a relationship, which struggles on in the survivor's mind toward some resolution, which it may never find.'