I take it as he was seriously in love with a girl, but she broke his heart. All that is gold is rusted. Nothing good remains of his love of her. They've come so far, but are going no where. HE is the battered lonely lighthouse. Tomorrow she's gone. and the mortality he's speaking of is how he feels dead without her, and it scares him so much. He doesn't want to think about it, because he wants to be able to move on and be free again...free of the pain. He has to keep going, and "soldier on". He asks her to take him, because he can't resist, but he must. He must stop thinking about her, and soldier on.
I take it as he was seriously in love with a girl, but she broke his heart. All that is gold is rusted. Nothing good remains of his love of her. They've come so far, but are going no where. HE is the battered lonely lighthouse. Tomorrow she's gone. and the mortality he's speaking of is how he feels dead without her, and it scares him so much. He doesn't want to think about it, because he wants to be able to move on and be free again...free of the pain. He has to keep going, and "soldier on". He asks her to take him, because he can't resist, but he must. He must stop thinking about her, and soldier on.