well, i delivered ds3 by myself. dp was in the room but he was on the phone to the ambulance people.it was a planned homebirth but things were happening a bit quicker than expected lol
bizarrely the day before he arrived we were talking about unassisted childbirth and i was feeling really strongly that i would like to give birth by myself and that i wasn't scared of it at all and i really didn't want anyone near me while i was in labour. got my wish pmsl
so, not quite your scenario, but i can understand where you're coming from!