Yet when you can't play a song where the drummer doesn lose time, of the singer doesn't forget lyrics, you would think you'd want to go over the song again to at least be able to play through. Some people are satisfied with seeing bands that are just "Good Enough" ...
So, why is the guitarist at fault here? Sounds like the husband and wife are not good enough or dedicated enough to pull this off. I'd dump them and keep the guitarist who's actually enthused enough about the project to drive it.