Sondheim's comments from that article:
Sondheim held on until a few years ago, when yet another Laurents jab appeared in an article. Sondheim declined to “stir up any goblins” by discussing specifics but said, “It’s not that I don’t talk to him—we have a working relationship. But the friendship is kaput, and we once were really close. I was the last long-term friend of his to say ‘enough already.’ The best part of our relationship was wonderful. He was a joy to write with. It was only when rehearsals started that the trouble began, especially if another director was involved. And he was always a great foul-weather friend: comforting, smart, a good guidance counselor. When I had my first serious love affair and it broke up, I was destroyed, and Arthur was one of the two people who steered me through the shoals. It’s when you’re miserable that he’s at his best. If you’re happy or, especially, successful—watch out. Arthur is the master of the imagined slight. I had the temerity to question some of the things he did to Gypsy when it transferred from City Center to Broadway—oy, was that a mistake. The screaming hasn’t stopped since.”