很有可能是假故事. Google 燕子对婚姻忠诚 (mate for life), 死了伴侣很少再找

If one of a swallow couple dies, the surviving swallow may experience a period of grief or bereavement, and may even be seen showing signs of sadness or despair. They might also be less likely to raise the nestlings alone, potentially abandoning them. Swallows, especially males, are known to form strong pair bonds and may struggle to find a new mate after losing their partner.