It's a funny thing with birds, sometimes they fall in love at first site, just as some humans do the same, but just as there are some people that just don't get along, people with personality clashes, the same applies with birds. Some birds just don't get along and there's not much you can do about it. You can try getting a very, very large cage loaded with toys so the birds have their own space but they still obviously don't like each other. Imagine being forced to be locked in a house with your worst enemy. That's generally how they feel. And to top it off, the one with eggs is trying to defend her "kids", whether they are fertil or not she will defend them to the end. They are her children and she's going to be extra edgy when she has eggs to protect. I suggest either finding a loving home for one or the other or just keeping them seperated from now on. Sorry for not having any good news. I love parakeets, I love birds, and I hope you don't give up on parakeets all together. They can be adorable, charming little birds, given the proper care and comfortable living environment.