Routine which operates outside time's usual rhythms
The author uses irony describing the moment when Cassandra takes care of Nell at the hospital: “The night nurse was there again, so Cassandra knew it was no longer day. The precise time she couldn't guess. It was hard to tell in here: the foyer lights were constantly on, a television could always be heard though never seen, trolleys tracked up and down the halls no matter what the hour.” An irony was in the fact that “a place relying so heavily on routine should operate so resolutely outside time's usual rhythms.”
The most favorite child, but not own
The author uses irony in depicting Hugh’s love to Nell: she wasn’t his daughter by blood, but he loved her more than his own daughters. Thus the author shows that true parent’s love is not dependent on biological connection, but on psychological, mental.
Wife’s duty
Rose thought that her husband Nathaniel adored painting her and thus her duty was to please him and ask him to paint her every day. But the irony was in the fact that actually it “burdened” Nathaniel: completely other things inspired him for drawing, but not his wife.
