Loved ones are starting to worry about me. Well, more precisely, about my singleness. My best friend emails me every day with helpful suggestions. Speed dating events. Dinners for singles in posh houses. She points at men in bars, saying loudly, 'What about him?' [They are always ordering two drinks]. And Cowgirl - who is newly in love, and having lots of great kitchen countertop sex, the bitch - even she has been fixing me with this look and saying, very firmly, 'You need to join a salsa class. Or a book club. You like academic types.'

My mother has been bearing down on me too. 'You know, you're not helping yourself,' she said. 'Think about your friendship circle.' 'What do you mean?' I said, a bit shrill. 'What's wrong with my friends?' 'Well, for starters they're all gay men. Who knit, for Christ's sake. Or women,' she replied. I took a moment to digest this. 'And that's just for starters?' 'Well, there's also the matter of Mike. He's the only straight man in your life. And he's congenitally single.'

They are right. So right. My friends are craft-hobbying gay men. And women. And my best straight male friend is stubbornly undateable.

Not that Mike would acknowledge that, of course. I tell him I think he has emotional problems. He says he just likes to be single. We've debated the issue many times. Occasionally, I've been a real bitch about it. But while I'm the one writing the blog, I can safely share with you that he does have emotional problems. He is terrified. Of what, only he, his counsellor and a little digging about in his family history, can say.

But it's not just about that. It's the whole men and women being friends business. I mean, in real life, as opposed to The Matrix universe that I seemingly inhabit, if a man and woman spend a lot of time together, email at length every day, speak at night, text each other support on bad days, say nice stuff to each other, like 'You are totally hot, if it wasn't for my snoring, I would sleep with you myself', generally this would lead to a date. Hot sex. Smug-couple happiness. A great frock, a large cake and, according to the scientists, three good years before indifference sets in.

But, no. It may feel, smell, sound and taste like romance. But it's not. It's called being friends with a man. I know I'm not the first to have had this conversation with Mike. He's been there before, with special lady friends. One of them is so in love with him, they've had to agree to a no-contact contract until she's fallen out of love with him, and hopefully in love with some great, deserving fellow who appreciates her fine qualities, including the planning perfect weekends away to the coast, and being a champion at pub petanque. With that CV, I'd bag her.

Don't get me wrong. Mike is a great, deserving fellow. But he doesn't understand why the intense friendships he has with women cause so much confusion and heartbreak. And who can blame him? Aside from his blokeish lack of insight, it is confusing. Not for the first time, I'm turning over those unforgettable lines from When Harry Met Sally, the first and best movie about men and women and modern relationships.

Harry: You realise of course that we could never be friends.
Sally: Why not?
Harry: What I'm saying is... and this is not a come-on in any way, shape or form – is that men and women can never be friends, because the sex part always gets in the way.

And it's the truth. The sex part does always get in the way. When men and women become friends, what is that attracts them to each other that is different to romance? Men rarely want intimacy unless it's also about sex, so if there's no sex, what is in it for them? And friendship is a bum deal for women, because, if they get intimacy, they want the sex too.

I suspect, when it comes down to it, men are just looking for the best of both worlds. You get woman friend totty and your single man status remains intact. Not bad.

As Harry says, on this basis, the friendship must ultimately be doomed. Or the guy finally caves. After all, it takes him 12 years, but Harry finally gets over himself and gives Sally her big day, coconut cake with chocolate sauce on the side and everything.

I am not waiting 12 years for Mike to realise I'm the love of his life. We won't be in Tiffany's (or even H Samuel) checking out the finger hardware. We won't be having kitchen countertop sex, Cowgirl style (goddamn it). We won't be having any sex. Mainly because, despite the bizarreness of being in a straight man-woman friendship, that's not going to work for either of us.

But the upside? Well, for starters, divorce is entirely out of the question. Beyond the hot sex with strangers, and the long-termish relationships that come and go like the tide, maybe even the single-mother baby I might one day have, I know I can rely on Mike being there in the golden years. Going shopping for comfy slippers at M&S. Arguing over who gets the last slice of National Trust tearoom Victoria sponge. Combining forces on naughty-word Scrabble. Zimmer races in the communal gardens of the retirement pad (the integrated Sat Nav model is mine, naturally). It's going to be a whole heap of old-person single fun.

Just in case, though, I'm checking out them salsa and book club options. I do have a thing for academic types.