Marc and Serge
Serge purchased an expensive painting which is the prize of his art collection. He's been waiting for months to be able to purchase it. Ironically, Marc believes it to be a ri off and not even close to art, as it's an all white painting with a few white lines on it.
Wedding Advice
Serge gives Yvan some advice about marrying his fiance: he advises him to call of the wedding. Ironically, Serge is giving marriage advice when he has yet to have a successful marriage himself.
Abuse
Serge and Marc clearly are on opposite sides of their beliefs about the painting. Ironically, rather than keeping their opinions solely to the art, they begin to berate one another for the failures in their lives. Thus making the battle between them much more personal and vicious.
Peacemaker
Yvan attempts to be the peacemaker between his feuding friends Serge and Marc. Ironically, by trying to please both of his friends by siding with them individually in private, he adds fuel to the fire of their feud rather than putting out the fire.
Offense
Serge has purchased the all-white painting with his hard-earned money. Ironically, Marc is highly offended by the purchase when in reality it has nothing to do with the state of his life. This reveals potentially Marc's true feelings for his friend and his need to have Serge be someone who kowtows to his beliefs.