13 Even in laughter the heart may ache, and rejoicing may end in grief.

Read Proverbs 14:13 Using Other Translations

Even in laughter the heart is sorrowful; and the end of that mirth is heaviness.
Even in laughter the heart may ache, and the end of joy may be grief.
Laughter can conceal a heavy heart, but when the laughter ends, the grief remains.