John Chrysostom

"Taking my leave of them, I went from thence." That is, 'I spent no longer time, being straitened and distressed.' And perhaps the work was even impeded by his absence. And this was no light consolation to them too. For if when a door was opened there, and for this purpose he had come; yet because he found not the brother, he quickly started away; much more, he saith, ought ye to make allowance for the compulsion of those affairs which lead us and lead us about everywhere, and suffer us not according as we desire either to journey, …

Homily 5 on 2 Corinthians ↗

Theophylact of Ohrid

That is, he was not there for a long time due to difficult circumstances. For although a great door was opened, that is, there was much work to do, yet for lack of a helper it met with hindrance.

Commentary on 2 Corinthians ↗

Thomas Aquinas

Then he tells why he had no rest in his spirit, when he adds, because I did not find my brother Titus there, i.e., because of Titus' absence. And this for two reasons. One reason was that although the Apostle knew all their languages, so that he could say: "I thank God that I speak in tongues more than you all" (1 Cor. 14:18), he was more skilled in Hebrew than in Greek, but Titus more in Greek. Therefore, he wanted to have him present to preach in Troas. …

Commentary on 2 Corinthians ↗