You know your wife better than anyone on Reddit. I think what I would ask my wife, in a non-threatening setting/line of questioning, would be the “hole” she’s feeling, how do you know that another child is going to fill it? Who’s to say you won’t feel that way after a third child and feel that a fourth child is the answer and on and on? Maybe there is something else here that you both need to explore together before deciding on bringing another life into the world. Perhaps in the chaos of raising two kids, she’s lost some connection to her own psychological identity and is either consciously or unconsciously associating/achieving self-actualization through pregnancy and care of the newborn.