One longing for the night (214)
Laura can't wait for her second taste of goblin fruit. She's like an addict: she can't focus on anything but where her next fix is going to come from.
Then sat up in a passionate yearning, And gnashed her teeth for baulked desire, and wept As if her heart would break. (266-268)
Laura seems to be showing signs of physical addiction. We see that she is actually in pain here.
Laura kept watch in vain In sullen silence of exceeding pain. (270-271)
Laura is secretive about her addiction, too. She doesn't even tell her sister what's happening.