DEAR ANNIE: My boyfriend of six years has multiple ailments. I try to be supportive and help in any way I can. But I find that, as he complains almost every waking moment, my patience is wearing thin. It also stresses me out and frustrates me because it is literally nonstop, and there is nothing his doctor or I can do. He has a sister who also complains nonstop about ailments, and she has lost relationships due to the stress it causes. I find myself avoiding spending time with him, and I feel sad and guilty. Do you have any advice for me? Other than the nonstop whining and complaining, he and …