Why is the first sentence in Pride and Prejudice ironic?

The first sentence in the novel Pride and
Prejudice, by Jane Austen, reads as
follows:

It is
a truth universally acknowledged, that a single man in possession of a good fortune must
be in want of a wife.

We can
sense a tone of irony in this sentence considering how Jane Austen personally felt about
the social expectations bestowed upon women, which mostly reduced them to the roles of
subservient wives.

Additionally, we can see irony in the
phrase "a man of good fortune in want of a wife" because it is an obvious play on words
that indicates that the wife would be one of the "objects" or "goods" that such
fortunate man would be able to get with his
money.

Moreover, the phrase is also suggestive of the
assumption that   a woman would only want to marry a man who comes across a fortune. In
other words, women will always be subservient because they will always aim to "marry
well", thus becoming dependent on the wealth of their
husbands.

Conclusively, the phrase carries within it a
wealth of innuendos which imply that money can basically buy everything, including the
love of a woman. Conversely, it also implies that marriage is an expectation rather than
a choice, and that it has better chances of succeeding when "a good fortune" is
present.