Maybe Skye is being overprotective of the nest box? In this picture she looks like she is past breeding cond. Can you block the entrance to nest box so she can't go in?

See if this helps with the aggression, if so leave it until they both look like they are in breeding condition and try again.

this picture was taken when i first got her, so she looks different now

i will post another picture when i get a chance

My birds bred on their own so I really have no merit. I just gave them a nest because the female layed an egg. My birds came to me as a pair that had bonded strongly at the pet shop.

 

I did have a bird as a child who killed her new playmate while I was at school. We bought her a lovely male and she murdered him. If there is this much aggression I would not put them together. I also do not know much about breeding but read that it is better when the birds have other couples around them.