So this question is for my aunt. So she has a love bird that is laying eggs and sitting on them. She and her mate do take turns. But they have been on those eggs for 3 months.
In future, maybe look up how long they should take to hatch, then allow another few days or maybe an extra week, then clean out any eggs that have not hatched (in this case all of them.) Three months sounds about way too long to me.
It might also be useful to date eggs as they are laid, or at least go through on occasion and mark them all (maybe once a week mark all the eggs that are already there?) That can help tell which ones to remove, which leaves more space and parental attention for the ones that may still have a chance.
With a chicken, having too many eggs can cause a bad hatch: some eggs stick out and gets chilled, then the hen rotates them around and different ones stick out and get chilled, and eventually most of the eggs have been chilled enough that they fail to hatch. I would assume something similar can happen with any kind of bird, although I have no idea how many eggs would be "too many" for a lovebird.
But what does a fertile love bird egg look like? I only ever candled chicken eggs.
I would expect the development to be similar in any kind of bird egg.
So they had me candle them and none of them had any visible embryos! They're were 20ish eggs. Cracked open some of the eggs and nothing. Also they had black stuff inside the egg? Kind of looked like mold.
I would guess that either the eggs were infertile, or they died at some point. Yes, there might have been mold inside after that much time sitting.
For why this happened, my first thought is to check whether the "male" is really a male. I don't know how obvious that is in lovebirds.
Other than that, maybe the eggs were too old when the birds started to sit on them? Or maybe the conditions were wrong as the eggs were being laid but before incubation started?
Or maybe the birds are just not managing to mate properly? Some chickens can have trouble with overly-fluffy feathers, geese often mate better on water than dry land, I've read that some birds mate while actually flying. I have no idea what details are important for lovebirds, just the basic idea that details can sometimes be important.
I notice that you have two threads with the same title and same question. I'm going to ask a moderator to combine them into one.