What's my cock goldfinch thinking trying to sleep inside the nest with the hen

Last two nights he was perched on the nest edge and tonight I thought he disappeared when I caught him out inside the nest just before dark.Is this normal?By the way he is so gentle no aggression whatsoever.They are a breeding pair from last year.
Another please guys, hen has been sitting tight and it's been 12 full days when I notice few Brocken egg shells on the bottom of the cage.Is it not enough days for hatching?I have noticed hen dropping food in the nest but can't be 100% sure

x This is my concern,cock roosting in with hen possibly going to suffocate young if any?