If the true mate was beaten and scared, he may have hidden in the area. Left to her own defenses, she certainly would not let the intruding male near her. Once the intruding male left, the female may have taken off to find her mate. If they were scared enough to flee, yes they could have abandoned the nest, eggs and area. They may have returned last night and you did not see them return. If this is not the case, then it may take a day or two to return or they may never return. It totally depends on their perceived level of threat. Finally, if the parents left for any significant amount of time and the eggs were left unattended, the parents will probably not return because the eggs would not survive without the mother sitting on them. The Regal Swan