I think I would "drop" it for the night... And remind him that tomorrow he will have all day to finish three applications..

Maybe it would be easier for him to "be alone" without "helpful, watchful eyes" at this point... Maybe turn on some background calming music as a way distract him from his frustrations...Gotta give the guy "thumbs up" for trying... And he may struggle, just don't let him feel your frustrations because it will only make him feel more frustrated... if that makes sense.........

I'd try to salvage the evening... Make him a cup of hot tea... and let him know you appreciated his efforts... and that tomorrow is another day...

(((((((((LMO and hubby))))))))))