AUNT ALICIA: Bad table manners have broken up more marriages than infidelity.
This emphasis on manners reminds us of a line from another Lerner and Loewe musical, My Fair Lady. In complaining about the terrible speech of Englishmen, Professor Higgins says, "The French don't care what they do, actually, as long as they pronounce it properly." Alicia's saying the same thing: appearances are everything.
GIGI: Why does grandmama stop me from accepting invitations?
AUNT ALICIA: She's right for once. You'd only be invited by ordinary people.
GIGI: What about us? Aren't we ordinary people? Why are we different?
AUNT ALICIA: They have weak heads and careless bodies. Besides, they are married. But I don't think you would understand.
GIGI: Oh yes, Auntie, I understand. We don't marry, is that it?
It's hard for Alicia to explain to Gigi exactly what's different about their unusual social situation. Alicia feels superior to ordinary people who aren't thinking every minute about obtaining jewels and carriages from wealthy men. She probably knows that courtesans would be looked down upon by married people, but still feels she's lived a more glamorous and financially secure life because of her past liaisons. How much of all this do you think Gigi understands?
AUNT ALICIA: Great kings don't give very big stones [...] because they don't feel they have to. […]
GIGI: Who does give the valuable jewels?
AUNT ALICIA: Who? Oh, the shy, the proud. And the social climbers. They think it's a sign of culture.
Lots of people thought that they could be admitted to the higher social classes if they spent lots of money and bought expensive presents. Aunt Alicia lets us know that's not possible. They're still unsophisticated and ignorant about the rules. Upward social mobility is a myth here.
GASTON: Ordinary common, or coarse common?
Gaston wants to know whether Liane is a poor romantic prospect because of her looks or her manners. Coarse would be worse.
GASTON: But a skating instructor.
HONORÉ: A skating instructor! It is always a skating instructor. Isn't that true Manuel?
MANUEL: Absolutely, sir. Remember dear little Madame Dumelle and Marmuluc the Terrible Turk?
HONORÉ: There you are. A wrestler from the Follies Bergere.
MANUEL: There was Madame Laura and the swimming coach. […] And Madame d'Albert and the riding master, Mademoiselle Monique and the weight lifter…Madame Bocher and the plumber.
HONORÉ: That's enough, Manuel. You made your point.
So the mistresses are always cheating with the regular guy even while they're being spoiled rotten by their rich boyfriends. Why would that be? Maybe the regular guys didn't treat them like possessions and were grateful to have them. Maybe having to pretend to be someone they're not got exhausting after a while.
GASTON: One can't be a Don Juan to one's valet, can one?
HONORÉ: I only keep him to prevent him from talking to others.
Honoré's just listened to his valet Manuel commenting on all Honoré's unfaithful girlfriends. Honoré says he'd get rid of him but then he'd just go gossiping to others. This little exchange shows how dismissive the rich can be to their servants.
HONORÉ: Play the game. Be gay, extravagant, outrageous!
Part of being "upper class" means playing the part, even when you don't feel like it. Gaston just never feels like it.
GASTON: Yes, I've had quite a full schedule lately.
MADAME ALVAREZ: Oh, so I've read! Oh you always do things in the grand manner. Your parties have filled the newspapers.
The best part about being in the gossip pages is never having to tell anyone what you've been up to lately. They already know.
GASTON: Forgive me, Madame, if I don't understand who you are keeping her for—some underpaid bank clerk who will marry her and giver her four children in three years? To see her married in white in a dingy little church to a plumber who will give her nothing but a name and the squalor of good intentions.
So being the mistress of a rich man is preferable to marriage to a working-class man. This would be an even more unbearably snobbish comment from Gaston if Aunt Alicia didn't feel exactly the same way. Gaston just can't believe that his social standing doesn't make this a no-brainer for Gigi and Mamita.
GIGI: To take care of me means that I shall have my photograph in the papers. That I shall go to the Riviera. To the races at Deauville. And when we fight, it will be in all the columns the next day. […] When it's over, Gaston Lachaille goes off with another lady. And I have only to go into another gentleman's bed.
Now we know—Gigi understands exactly what's in store for her in her social role as mistress. She'll be living in a fishbowl and have to do things that don't interest her at all. And when it's over, Gaston's free to move on to someone else, even get married to someone in his own society. Gigi will be stuck forever in the demimonde once she's been in that role.
GASTON: Here is a girl, living in a moldy apartment, decaying walls, worm-ridden furniture, surrounded by filth!
We're confused, Gaston. You seemed totally fine there the other day, drinking champagne with the old woman and the little girl. It's the only place you were happy What's changed? His pride was hurt, that's what, so he stoops to insulting Gigi's family and social status.