The old man brings a touch of negativity to Leila's first dancing experience. However, his words constitute important social commentary. First, female beauty (and by extension, youth) is greatly prized in Leila's society. Second, the old man has been dancing for thirty years; his continued participation in formal balls (despite his age) indicates that the prevailing standards of beauty apply only to women.
Sadly, a woman's worth is often defined by her attractiveness quotient. The old man is telling the truth about the chaperones, who are no longer deemed "kissable." However, his words are difficult to hear, and they make Leila feel uncomfortable.
And your heart will ache, ache"–the fat man squeezed her closer still, as if he really was sorry for that poor heart–"because no one wants to kiss you now. And you'll say how unpleasant these polished floors are to walk on, how dangerous they are. Eh, Mademoiselle Twinkletoes?" said the fat man softly.
The chaperones are despondent because they can never again command the attention they once enjoyed. Despite their frustrations, they must bow to prevailing standards of decency and refrain from voicing their discontent. To comfort themselves, they complain about the "unpleasant polished floors." The old man's words also reveal another truth. On account of his age, he is expected to behave with decorum. Society rightly demands this of him. However, he too must keep his regrets to himself, just like his female chaperon peers.
True, he may not be held to the same beauty standards as the women, but he understands that his age is looked upon as a disability in the current setting. Like the female chaperons, he is no longer young, and no one wants to kiss him either. Even Leila thinks he looks old and shabby. She tries to be kind but privately wonders why he isn't on the stage with the other parents. So, the old man performs a duty, but like the female chaperons, does not enjoy it.
His soft, cynical words highlight the importance society places upon youth and physical beauty.