There is this man - the Norwegian.

I met the Norwegian in late spring. We bonded over a shared love of backgammon. I know, I know - backgammon? Does no compute, right? File under 'Belle likes Ivor Cutler and real ale and the Simpsons' and let us move on, shall we?

Anyway. The Norwegian and I meet regularly for mutual appreciation of beer, board games, and Simpsons (as far as I know he is unaware of the specific charms of Mr Cutler). Every time we part my face hurts from smiling and laughing. He is tall and kind and has nice hands and impeccable taste in watches. He is the sort of chap I typically find attractive, a sort of which A2 is the most notable example.

We call these meetings Dancing in the Donut Rain. This appeals on several levels, being a keen dancer often found at the recreational classes at... um, a studio near me. If you don't get the Donut Rain reference, watch more Simpsons. It represents an alternate present. For an hour or two I bask in friendly companionship and the knowledge that whatever this is, it isn't going anywhere. Because he has a partner of ten years and I have a line I will not cross regardless of my own relationship status.

I know. The whore has standards after all.

There are several reasons why the line holds firm: the Norwegian idealises me too much. His distaste for even the most peripheral mention of T is no secret. He is, by his own admission, in love with me - or at least the me he knows, the me whose fierce deployment of the doubling cube, habit of arranging beer mats parallel to the table edge, and opinion on all things Bill Murray are defining characteristics - the pre-Belle me.

Post-Belle me sees his behaviour and recognises three things:

1. Regardless of whether I was single, being with him would hurt his girlfriend, a woman I've never met,

2. Being with me would hurt him whether he stayed with or left her, and

3. Even if 1 and 2 were manageable, he is not a man who could handle my past.

This is where an affair diverges strongly from sex work. This is how I could have clients who were married and never care, but a friend with a significant other is off-limits. He cares more than I think he should and it is worrying. Lately he has been starting arguments with his woman, and last month even moved out. Maybe that was coming anyway. Maybe not. What my existence does to his relationship is very much my business. Because any involvement wouldn't be about just sex, because something I do could hurt someone I don't even know.

His interest, in other words, is very flattering but simply not sufficient reason to play. Oh, the irony - sex work made me more selective about which men I pursue and why rather than less so. A bit more ethical. More of a grownup, perhaps.

Tomorrow, I think, will be our last dance in the Donut Rain. It is not an ultimatum, it is not a threat, it is simply the way it has to be. I will miss him but know it is the right thing to do.

I'm happy and I'll punch the man who says I'm not.