If you live with a writer, or if you watch one very carefully in their day-to-day lives, you will know for certain when they're engaged in their art. They smile more. They have more confidence (even if it is a mere modicum). They walk around in a pleased but distracted fog, because they can hear their characters' voices and see glimpses of the worlds they've built. It takes a little more effort than usual to get their attention. They hum to themselves. They are happy.
If they are not engaged in writing, however, you will see something significantly different. They get emotional, or they withdraw. They are easy to find; they're either in the kitchen, staring listlessly into the refrigerator, or they're in the bar, losing against their half-empty glass in an impromptu staring contest. They either avoid their computers, the scene of so much happiness in the past, or they engage their computers too much, trying to milk inspiration from Minesweeper, Bejeweled, or Facebook. If they could, they would sleep most of the day in an effort to fast-forward through their lives to the point where the voices in their heads are once again their characters' friendly voices, instead of the chanting voices of Failure. They are obviously not happy, and their symptoms are similar to, if not the same as, true depression.
There are two reasons for this tragic state for writers, and I can't decide, frankly, if it's worse for the writer to have nothing to write, or have something to write, but be kept from writing. The one form of deprivation is referred to as writer's block, and it's a cold killer of joy. I've described the euphoria of having a project to work on -- you have a cacophony of voices in your head, and you never feel alone. To have those voices suddenly vacate -- to have no companions and no preoccupation -- is awful.
But the other form of deprivation, to have those voices pleading with you to spend time with them, to make time for them, and to give them a chance to live and breathe and act and fulfill their destinies -- and to not be able to give them what they want -- that's awful, too.
So is it worse to have friends and not give them your time, or is it worse to have no friends to disappoint?