Is my pet bird dying?
Call a pet store that specializes in birds and ask about this. Perhaps he has mites. Often, the people in these stores can venture a guess. Another thing you could try would be blogs for caged bird owners. Consider whether the bird is in a large enough cage; gets proper diet (look that up for this bird); could have mites or other skin irritation; is in proper temperature; gets bird vitamins; cage cleaned adequately and often enough; water changed every day; cage in an area that is near people but not in main traffic area. Look up are of Lovebirds and be sure you are following the normal guidelines. I would start with some bird vitamins. Since this bird sounds stressed, you ought to go right to one of these bird specialty stores and ask about his health, and how to properly tame him once he is feeling better.
The bird is lonely and the best thing to do is sing to it and speak lightly. Don't move fast...move slowly. if the bird cage is in a highly used area of the house isolate it to a corner of the room.