This is probably either an isolated incident or most likely an old wive's tale. We have found that male swans will go about their lives with or without a new mate, while a female will find a new mate to propogate the species. We have never heard of any animal throwing themselves into harm's way because a mate dies unless it is a human!!!

Swans usually mate for life, but if something bigger and better comes along, they will re-mate. The Whooper Swan has a 6% divorce rate. The Regal Swan