Oscar Wilde mocks the Victorian society, he thinks the society is pretentious, full of self-importance, ignorance, and idleness. He thinks that upper-class Victorian society has some ideas that are nonsensical.
His character Ernest/Jack leads a double life, he was discovered as a baby in a handbag in the cloakroom of Victoria Station. He was adopted and leads a double life because he portrays himself as a major landowner and a number of servants that hide his poor past. He creates a false brother that is an irresponsible black-sheep, so he can lead a scandalous life without getting in trouble.
Jack has a respect for all these Victorian rules and societies social rules - such as marriage and the money that comes with it - even though he knows they are false the same way he is. He pretends to disapprove his own behaviors as a way to portray a right and just character to the Victorian society.
Well he might be frightened because of the words he is using to describe what is happening. He uses the word pitifully thin which might make him frightened because he just woke up from a dream.
