It's rude to insult someone's intelligence.
Shyla is watching her husband having trouble putting together a piece of furniture.
Shyla wants to vocalize her observations to her husband.
Shyla makes a tongue in cheek crack at her husband's efforts to assemble the piece of furniture.
Shyla comments on the instructions seeming very straight forward which implies things about her husbands abilities.
Shyla's husband laughs at her observation and invites her to try her hands at it in playful manner which they both laugh at.
Shyla's husband is miffed by the insinuating observation and the couple get into a squabble.