I have heard that they are "merrymaking and lovemaking" the entire time. But if there is someone more familiar with the lives of fairies, I would love to learn about their culture...at least some sources about it.
Check out: Fairy Legends and Traditions of the South of Ireland by Thomas Crofton Croker http://www.gutenberg.org/ebooks/39752
The Brothers Grimm translated Crokers Fairy Legends and provided a summary in the beginning of their translation. Below is what they said, loosely translated and paraphrased:
Fairies always live in large groups, never alone or in pairs. They are invisible to humans. Their houses are in rock cracks, caves and old giant hills. They love music. They celebrate under roomy mushrooms. They disappear at first light. They love to play ball, which they play with great eagerness, sometimes they come into dispute when playing.
There is of course much more.
See also: Lays and Legends of the North of Ireland by Cruck-a-leaghan, Slieve Gallion.
In Irish mythology, the fairies called the Aos Si (the People of the Mound), fairies would protect their homes in fairy rings, hawthorn trees, and the woods. They would also spend their time kidnapping trespassers or replacing children with changelings if they break fairy law. These fairies mainly came to the Mortal World between dusk and dawn. Some fairies like the bean sidhe would announce the coming death of mortals by wailing and keening.