Antonyms of painful:
painless, unpainful, good, pain-free, comfortable, comfy, pleasant, curative, healing, helping, remedial, indolent, bearable, endurable, supportable, sustainable, tolerable, livable, sufferable, survivable, acceptable, allowable, reasonable, gratifying, pleasing, sweet.
Examples of usage:
  1. It would have saved us a good many anxious and painful hours.
    "The Squire's Daughter", Silas K(itto) Hocking.
  2. If a visit to him would not be painful, he has begged it may be this morning.
    "The Gamester (1753)", Edward Moore Commentator: Charles H. Peake Phillip R. Wikelund.
  3. It is naturally a deeply painful subject to me.
    "A Terrible Secret", May Agnes Fleming.