What happened to Paul while he was distressed about Titus at Choas?

At Choas, Paul found an open door from the Lord to preach Christ's gospel, yet he had no rest in his spirit because Titus was not there. While he was distressed over Titus's absence, the Lord came upon him with something totally different than he had expected.

Les explains that Paul and Titus had arranged to meet at Choas, the seaport town identified as ancient Troy. Since there was no mail, telegraph, or phone, Paul had no way of knowing what had happened to Titus. When Paul came to Choas to preach Christ's gospel, a door was opened to him of the Lord, but he had no rest in his spirit because he did not find Titus his brother. While Paul was distressed over Titus's absence and wondering why he was not there at the appointed time, the Lord came upon him with something totally different, contrary to what Paul had thought he would do. Les suggests these two matters were almost a clash in Paul's thinking.

2 Corinthians 2:12

Furthermore, when I came to Troas to preach Christ’s gospel, and a door was opened unto me of the Lord,

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Why was Paul so heartbroken and distressed in 2 Corinthians 2?

Paul was heartbroken and distressed because Titus had not been able to keep his appointment at Choas. He had no rest in his spirit because he could not find Titus his brother. Yet he left them and went into Macedonia, obedient to the Lord’s call to preach the Gospel there.