The first sentence uses exaggerated techniques to write that the high platform soars into the sky, and the second sentence adds that the high platform is endless and extremely high.
The last four sentences, imagine that the old lover is thinking about himself. No matter how high the platform is and how far the road is, they can't stop missing them, so as to express their feelings of missing. However, Shen Shi's "thinking" does not necessarily refer to a lover. The last four sentences, in the self-questioning and self-answering, reveal the sadness and helplessness that are difficult to resolve.