What to do when a married man comes on to you?

He's attractive and he's flirting with me, but I really wish he wouldn't.

We're having one of those conversations – it's stilted, like a car, stopping and starting on a journey to nowhere in particular. Ten minutes ago we were chatting amiably, but now he has decided to up the ante and is refusing to take no for an answer.
None of this is said, of course. There's a subtle interplay between language and body language that happens during flirting. Words are necessary, yes, to carry the conversation forward, but what's really going on is unvoiced, at least initially.
He touches my hand; I remove it and pick up my glass. Five minutes later, he brushes my thigh and I shift my leg a few inches away from him. Neither of our very definite hints are having the desired effect.
Frankly, I don't know why he's bothering. To amuse myself, I enumerate the possible reasons.
Option number one: my skirt. Sitting down it's a lot shorter than I'd realised standing in the dressing room mirror a week before. It's more than half way up my thigh and no amount of rearranging, twisting and pulling is going to make it any longer.
Option number two: he thinks I'm an easy target. This is partially circumstantial and partially my own fault. I am friendly, perhaps too friendly on occasion, but he is my friend Emma's cousin, so rudeness isn't an option. Add to this the fact that I'm your trusty HP sex columnist and wearing a skirt that doesn't leave much to the imagination, and perhaps it's understandable that he has got the wrong impression.
Option number three: it's a numbers game. It's late, and for a Saturday night, the pub is remarkably quiet. There isn't a lot for him to choose from. He's zoned in on me because there just isn't anything else going.
There's Emma, of course, but this is Dublin where thankfully most people observe genetic niceties and don't do the nasty with family. There's a cute girl over in the corner, but she's gay. I know this because I was chatting to her earlier.
Then there's Haley, my sister-in-law. You'd have to be a brave man to try your luck with her. Not because of Haley herself, who is lovely, but because she comes attached to my brother. He's a big guy, and since he shaved off his hair he looks like he supplements his income breaking bones for the Russian mafia. In reality he's a code-writing, computer-fancying, guitar-strumming geek who buys pints for amusing strangers – we Sextons are all friendly – and has been known to give the coat off his back, literally, to the homeless, but that doesn't stop people from crossing the road when they see him walking down a dark, empty street.
Over towards the back there are a few more girls. Three or four drunken young ones and the rest are spoken for. I appear to be the only straight, unattached female who is neither family nor jailbait – thus my number has been called. There's just one problem – I don't like him, at least not in that way.
I cross my arms and scan the room looking for my friends. Emma is nowhere to be seen. Outside smirting – smoking and flirting – is my guess; she had her eye on someone earlier. David is on the far side of the bar, chatting to some random person. Haley, sensing her drink would be a long time coming, has gone over to get it and has gotten roped in to the conversation. Thus I am a captive audience, stuck at the table with the jackets and handbags and the cousin.
He touches my shoulder and asks me a question, his hand lingering a bit longer than necessary.
"It's getting late," I say, pointedly yawning. "I better get going soon."
"I could join you?" he suggests.
"I don't think so," I say.
"Why not?" he asks.
I don't see why I should be obliged to give him a reason. Firstly, I haven't given him any encouragement; secondly, and more importantly, he's married.
There are plenty of men and women who will sleep with married people, and plenty of reasons why they do it.
There are women and men who find themselves emotionally and sexually drawn to someone who is already married. If their feelings are reciprocated the temptation may be impossible to resist. They never set out to be the third party in someone else's marriage and for the most part, are shocked and saddened by their own behaviour. Condemned by themselves and by society, theirs is an impossible situation, where at least one person will get hurt.
That's not the case here.
There are those who purposely target married people because they see a wedding ring as a challenge and believe that having sex with such a man or woman will affirm their own attractions.
That's them – not me. My self-esteem is all right, thanks.
Then there are women who proudly claim that being a serial mistress is something of a career choice. Quite frequently having been the victim of infidelity themselves, they are unwilling or unable to commit and see married men as emotionally less risky. They would rather be the duper than risk the possibility that one day, they might be duped again. Because love or the desire for a long-term relationship is not part of the equation, for the most part they have no desire to break up their lovers' marriages – but of course, if the affair is discovered, they may well do that.
Certain men prefer married women, believing – erroneously or not – that they will make less demands on their time and be more sexually willing than single women.
For others, it's the excitement of an affair that motivates them. The sneaking around, the risk of being caught, the lies, the heady excitement of breaking a taboo gives the sex a more piquant edge. It's not the sex itself that's exciting – it's the context. Strip that away, and in many cases the sex becomes routine.
But that doesn't appeal to me either – I find lying and liars depressing.
Some people are naturally monogamous, but the truth is most of us are not. We may try to be, we may even succeed, temporarily at least, because religious and social codes tell us that anything else is sinful, immoral and wrong.
I suspect that were I to get married, I would find myself struggling against the shackles I'd placed upon myself. And so, I am sympathetic to the married man or woman, who while desiring the comforts of a relationship, a life, a family with one person, still find that the sexual appetite has not been curtailed by a piece of paper and a gold ring.
There are couples that make accommodation for that; couples whose relationships are built on plenty of things other than sexual fidelity and who leave the door if not open, then at least a little ajar.
But that's not him. I know because I asked.
If I were married, would I care if my husband found it impossible to be faithful for the next thirty years? That every now and again he was lead by the desire to experience something or somebody new? The truth is, no.
But that's me – not his wife.
If, he admitted, she knew what he was up to, trying his luck on the town whenever he could, she would probably divorce him.
I am certainly not the best person to be the guardian of other people's morals. It's his life and his marriage, and what he chooses to do or not do, is his business, not mine. But would I want to be part of the reason somebody filed for divorce? No. Would I do something knowing full well another person would be hurt by my actions? Not if I could help it, and this time I could.
I gathered up my bag and jacket, and walked away.