Sometimes it's hard to know where addiction ends and the person begins: despite not going to meetings, R is still sober. Something in his behaviour, however, suggests that he is struggling. He flits from being manically euphoric one minute, to listless and fidgety the next.

This evening, he seems irritated by everything: especially the presence of us, his family. I watch him clear the table before I go to my weekly meeting for families affected by addiction.

"Is there anything for me to eat?" he says. "I'm starving."

"Well, there's stuff in the fridge." I know that when I return later, R will have eaten nothing.

In the past, I would have stayed at home and perhaps missed my meeting, in an attempt to get to the root of R's unhappiness. I would have goaded him for answers; I would have consoled and advised him.

Not tonight. I need to go along to the group because I find it incredibly helpful and supportive, and I don't want to be late.

I have suggested on many occasions during the past week that R should talk about things with others when his mood darkens, but my advice has been met with: "I'm fine. I can deal with this."

As I shout my goodbyes to the children upstairs, I stop myself saying: "Be good for daddy. Don't make too much noise." I am slowly learning not to pussyfoot around R, and I have to lead by example. They are children, and sometimes they play loudly and as a father, he will have to deal with it.

As soon as I step out of the door and into my car, I feel an immediate sense of relief. Even the heavy traffic doesn't dampen my good mood. I play Prince and sing along loudly.

The meeting is busy, with a few newcomers. I catch sight of an unfamiliar man sitting opposite me. He is tall, handsome and resembles a younger, smarter Jeff Bridges. I notice he's wearing a suit that is the wrong side of shiny, but I find his attractiveness distracting. He exudes kindness even before he introduces himself to the group as we go around the circle.

His wife is an alcoholic. He explains how her drinking has become so out of control that she has – on more than one occasion – forgotten to pick their son up from school. He seems genuinely terrified of what the future might hold, because although she has not touched alcohol for more than a week, the chances are quite high that she will do again.

Every one of us in the room could focus on the major differences in the situation he is describing (we are not all husbands or wives of alcoholics – some of the group are parents, or children) but it is the similarities in the patterns of behaviour between ourselves and the addict that many of us are, unfortunately, all too familiar with.

As he speaks, my mind begins to wander. I am an impolite daydreamer, because often when I'm thinking about someone who is present in the room I unintentionally stare at them.

I start to think all sorts of inappropriate things about "Jeff". What would he look like naked, on the loo, or tucked up in bed next to his wife? Then I imagine us lying side by side, his hand wandering over to stroke my thigh. I see us kissing, his warm breath against my cheek, and I even fantasise about the smell of his skin.

Then my mind strays yet more, and I become annoyed that we will have to move to a bigger house if we become a couple, because we'll have a small army of children between us.

With an abruptness that coincides with a latecomer opening the door, I bring an end to this ridiculous train of thought. I am aware that I have been looking directly at Jeff for a long time, and he has stopped talking.

The sound of my own voice startles me.

"Will you leave her if she drinks again?"

"I don't know. I've said I will, but I've said that before when she's stopped. When she starts again, I think that maybe I'll give her just one more chance to get better."

On the drive home, I wonder what I will do if R picks up a drink again. There is something in his present mood that makes it seem very likely.

"Good?" R asks when I'm home.

"Good," I mirror laconically as I turn to leave the room. Like a child, I think, "Jeff would never be as miserable as you're being."