"In Married Life Three Is Company And Two Is None"

Context: In this comedy by the Dublin-born wit Oscar Fingall O'Flahertie Wills Wilde, Jack Worthing is in love with Gwendolen Fairfax, daughter of Lady Bracknell. His friend Algy is Lady Bracknell's nephew. Algy is a bunburyist, that is, he has invented an invalid friend, Bunbury, whose uncertain health calls Algy from London whenever it is desirable to escape one of his aunt's dull parties. Jack, as a means of occasional relief from his soberness as guardian of a young lady, has invented a reprobate brother called Ernest, who lives in London. He tells Algy that upon marriage, he will get rid of Ernest, and advises his friend to kill off Bunbury. Algernon scoffs at the advice.

Nothing will induce me to part with Bunbury, and if you ever get married, which seems to me extremely problematic, you will be very glad to know Bunbury. A man who marries without knowing Bunbury has a very tedious time of it.
That is nonsense. If I marry a charming girl like Gwendolen, and she is the only girl I ever saw in my life that I would marry, I certainly won't want to know Bunbury.
Then your wife will. You don't seem to realise, that in married life three is company and two is none.