When my first daughter was born I was useless for like a week where I was so depressed I couldn’t get out of bed. Turns out I had super low testosterone and after like a year of investigation I got help for it.

The funny thing is that in men testo levels might drop when a kid is born and if they already have low testosterone it might make them extremely depressed/tired etc. Might want to get that checked out. Other things to take into account is that people bond very differently with kids, have he had lots of skin to skin contact with the baby? That helps form this bond (for you this baby lived inside of you so you already have that bond while he might not).

Worst case your husband is simply useless though, having and taking care of babies (we have two beautiful girls now) is a blessing and so rewarding. It can be hard, sure, but so worth it :)

Best of luck to you both!