Will lovebird protect unfertile egg

Well, when I tap my nestboxes they immediantly get out, unwilling to even attempt to protect their clutch from me. However, if you mean the sense of a male lovebird protecting his offspring, then yes. Lovebirds or any bird will think the egg is fertile even if it is infertile or a dummy egg. They usually reject the egg once they sat on it for a week or two.