She'll get out to eat! Don't worry! (normally whilst you're not looking! Lol!) If you're worried, take the eggs away from her. They won't be fertile unless she mated with a male bird. If there's a chance they might be fertile, I'd suggest either taking the eggs away completely or replacing them with plastic/wooden dummy eggs. If she's on her own it might be hard for her to bring up any chicks without the male birds help. I don't really know much about bourkes but I'm sure someone will be along to help more soon (and my advice is normally wrong!!).
If she is single it is a waste of her resources incubating eggs - unless like George asked if she mated with a male at anytime? Laying eggs is a drain on her calcium reserves and unless she is with a mate it is a waste.
She'll be fine if they're not fertile. It's a good idea to let her sit on them anyway or she might just keep laying and make herself ill. Also, make sure she has a cuttle bone as creating eggs uses a lot of the birds energy/vitamins and cuttle bone will help to replace it.