Male cockatiel thinks he’s setting on eggs

My female laid a deformed egg size bed f a penny. The male went to the box and threw it on the floor of the cage. I put it back He did it again. It broke. I threw it away but he has started setting in his forage box nesting. For two days now he just sets there. He eats. Gets up moving around in the evening flying etc. mating still with his partner. This is so weird for him. I uncover the cage in the morning and he’s setting in the box. He’s acts more like the female. I was starting to get kind of worried.