If we go by the writing style of the author, Oscar Wilde, the first point to consider is the irony of the title. Wilde used satire as his preferred medium for comedy. These comedies, which mock the upper classes's obsession with class and propriety, are called "comedies of manners" for that very reason.
That said, the irony of the title of this play is the first point. The collateral damage that this irony leaves behind makes the other points up for consideration.
1. The "ideal" husband, which Sir Robert Chiltern is, as his title suggests, a "gentleman." He is admired and celebrated by all, especially his wife, Lady Chiltern.
However, this man is far from ideal. He is actually what we can call a "schemer." At least that is what he was when he first made his first fortune as the inside informant of a Baron Arhheim. This Baron used Chiltern's inside information to invest and earn millions for himself and Robert. As you know, in the world of trade and business, everyone is expected to play fair and not try to get ahead of the other buyers and traders. Inside information entails that Robert Chiltern got secret information about a good business trade deal and snitched it to Arnheim. In today's world that is considered illegal. It would have been a dishonest and Illegal practice back in Victorian times, too.
We now know that this "amazing" man is quite dishonest.
2. This ideal husband is willing to engage in blackmail to keep his secrets! Instead of owning up to his past, redeem himself, and make a show of decency, Chiltern pays off a very shady woman (the former lover of Baron Arhheim), Mrs. Cheveley, to keep the secret that she holds over him.
As the play develops, we realize that everyone has pasts to confront, fears, and demons to fight. Even Lady Chiltern has a conflict: whether she should support her husband or not, once she finds out about his truth.
Hence the main points to consider are:
- Nobody is what they seem to be (Sir Robert)
- Everyone has secrets (Mrs. Cheveley, Lord Goring, Sir Robert, Baron Arhheim)
- Everyone and everything changes in some degree or another, no matter how much you deny it (Lady Chiltern)
- Victorian women are still expected to be the primary supporters of their husbands (Lady Chiltern)
- A respectable title (Sir, Lord) may bring you a higher social class, but not a higher moral status (Lord Goring, Sir Robert)