Why didn't Paul know what had happened to Titus when Titus failed to arrive at the appointed meeting?
Paul had no way of knowing because there were no means of communication available in ancient times; he could not mail a note, telegraph, or phone. Although Paul and Titus had agreed to meet at Choas, ancient Troy, Titus's failure to arrive left Paul with no way to learn what had happened.
Les explains that Paul and Titus had made an agreement to meet in the seaport town of Choas, which was actually the ancient city of Troy. At that time, they could not just drop a note in the mail, or send a telegraph, or phone, or anything like that. So when Paul came to Choas to preach Christ's gospel and a door was opened of the Lord, he had no rest in his spirit because he found not Titus his brother. Since they had no means of communication, Paul had no way of knowing what had happened to Titus or why he was not at Choas at the set appointed time. At the same time he was distressed about what may have happened to Titus, the Lord came to him with something totally different, contrary to what Paul had thought he was going to do, and the two were almost a clash in his thinking.