John Chrysostom

"For Demas hath forsaken me, having loved this present world." He does not say, "That I may see thee before I depart this life," which would have grieved him, but "because I am alone," he says, "and have no one to help or support me." "For Demas hath forsaken me, having loved this present world, and is departed to Thessalonica"; that is, having loved his own ease and security from danger, he has chosen rather to live luxuriously at home, than to suffer hardships with me, and share my present danger. …

Homily on 2 Timothy 10 ↗

Theophylact of Ohrid

He does not say: I wish to see you before I die, so as not to grieve him; but rather — since I have no one who would help me in preaching the gospel, hasten to come. What does "having loved the present age" mean? That is, having loved ease, a safe and quiet life, he preferred to enjoy himself at home rather than suffer hardships with me. …

Commentary on 2 Timothy ↗

Oecumenius

For Demas has forsaken me, having loved this present age, and has gone to Thessalonica; Crescens to Galatia; Titus to Dalmatia. Only Luke is with me. Take Mark and bring him with you, for he is useful to me for ministry. having loved this present age. Having become safe and secure, as he thought. For Demas preferred to indulge in luxury at home rather than suffer hardships with me. But Paul does not want to slander this man, rather to support us so that we do not become weak. Crescens to Galatia. …

Commentary On 2 Timothy ↗

Thomas Aquinas

The reason he summons him is because he has been deprived of all human companionship: first, he was abandoned by one of them because of his guilt; second, because he had sent others to preach. He says, therefore, "for Demas has left me," i.e., he preferred the love of this world to loving me: "if a man loves this world, the love of the Father is not in him" (1 John 2:15). Crescens, one of his disciples, is gone into Galatia, sent by the Apostle. …

Commentary on 2 Timothy ↗