I am no expert, but I would guess that exposed eggs will be taken by predators, and the Male won't be able to hatch them, if he sat long enough for that he would starve, which us why it needs a pair to take it in turns incubating and feeding.
It isn't known how she died yet Tilly, only that she was found dead a few days ago. He sits on them for long periods but then leaves probably to feed. I haven't seen the other female for a while and haven't seen her on the eggs at all.