Inside Earth by Poul Anderson

I will never forget one certain evening.

Hawkins and I had come over to Barbara's for supper, and the three of us were sitting now, talking. Wieniawski's Violin Concerto cried its sorrow, muted in the background, and the serene home she had made of the bare little functional apartment folded itself around us. Then Kane dropped in as he often did, with a casualness that fooled nobody, and sat with all his soul in his eyes, looking at Barbara. He was a nice kid. I didn't know why he should annoy me so.