Edema (swelling) around the eyes is, unfortunately, a common symptom of Lupus. It may be that his decrease in Prednisone is resulting in the increase of symptoms. This, too, is common. This swelling can also be an indication of Lupus Nephritis (inflammation of the kidney). It might be advisable that your boyfriend bring this condition to the attention of his doctors so that the exact cause can be determined and appropriate treatment, if needed, can be initiated.
I wish you both the very best and please let us know what he and his doctor decide.
Peace and Blessings
Look For The Good and Praise It!