Levity

They're handling the issue with levity.

On the eve of the bridal day, Lucy appeared to have one of her fits of levity, and surveyed with a degree of girlish interest the various preparations of dress, etc., etc., which the different members of the family had prepared for the occasion.

Most of the confidences were unsought — frequently I have feigned sleep, preoccupation, or a hostile levity when I realized by some unmistakable sign that an intimate revelation was quivering on the horizon; for the intimate revelations of young men, or at least the terms in which they express them, are usually plagiaristic and marred by obvious suppressions.

Most of the confidences were unsought - frequently I have feigned sleep, preoccupation or a hostile levity […]

[…]it would really seem as if there was something nomadic in our natures, a principle of levity and restlessness […]

Hydrogen […] rises in the air on account of its levity.

For though it be something wonderful to tell that any should have hearts so hardened, in the midst of such a calamity, as to rob and steal, yet certain it is that all sorts of villainies, and even levities and debaucheries, were then practiced in the town as openly as ever: I will not say quite as frequently, because the number of people were many ways lessened.

[…] or do the people joy less than common in their levities?"

His incorrigible levities had probably lost him the countenance of most of his more serious acquaintances[…