If you're planning on being a parent, it's necessary to also plan for all the gross and dirty, nauseatingly nasty bodily fluids that go along with it. Sticky fingers, chunky food all over their faces, cleaning up regurgitated applesauce from their brand new shirts, and constantly changing biohazard-level diapers is all part of the deal.
If your partner or co-parent isn't at all interesting in handling the messy parts of the job, you must be prepared to either find a new team member or do everything yourself without complaint. While it might seem like an okay idea to volunteer for every diaper duty before you're faced with the endless task, things can escalate even further when the person refusing to do the job also wants to critique how you're doing it. You have someone to say about my performance of the 3 AM, running on 0 hours of sleep diaper disaster? Do it yourself then!