According to Bernard Geberowicz, psychiatrist*
“Some men have trouble deciding because of a classic fear of commitment, synonymous with constraints and loss of freedom. But above all, the arrival of a child is an irreversible act, which directly confronts them with their sense of responsibility. Sometimes, the question is also asked too imperatively by their partner. They then begin to intellectualize and rationalize the answer... And the more arguments one looks for why having a child, the more arguments one finds for not having one! Another reason, men have in mind the idea very widely transmitted – wrongly – that the arrival of a child means the end of their couple. That their wife will devote herself to the baby by putting them aside. »
*author of "The couple facing the arrival of the child, overcoming the baby-clash", at Albin Michel.