Hard to believe, but this exact situation just happened to our female swan. They had been a pair for 11 years. Now, the male wanders aimlessly near the nest even sitting on it. It's really heartbreaking. My brother-in-law, an avid outdoorsman, took the remaining eggs and put them in an incubator as the male swan wasn't consistently sitting on them. We hope and pray they hatch. It's especially sad/disappointing as my son who is 2 1/2 and me have been watching them daily and anticipating the hatching. I know that Mute's will accept a new mate so we are going to begin searching for a female for him. I do hope that the male at your complex is able to find a new mate as well.