It's been a couple years since the demon were gone from this earth

Sadly nothing exactly has happened between Zenitsu and Nezuko but some other things happened to another women were it led it to be outside a room, waiting

He was about to be a dad

Then the Midwife came out with the small bundle and handled it to him before stepping back and watching him for a minute

Zenitsu just stares at the bundle with emotions going through him