TTC OR STOPPING ?😑

My fiancé & I are TTC , we already have a son and we are now strongly wanting a girl. The other day we talk in about it and he's telling me he doesn't feel comfortable changing her diaper ? Okay I can understand that to an extent but not one diaper ? I already did everything when it came to my son being a new born because he didn't no how and I had to teach him but is this normal ?