We’ve all been there: a message flashes up on your partner’s Facebook page, and it’s some (beautiful) girl, being obviously flirtatious. Your rational brain calmly tries to explain, but is slapped down by the psycho bitch you suddenly become, screaming: HE LOVES HER!

The internet is a neurotic girlfriend’s enemy, and we can’t switch it off (I’ve tried). It’s there 24/7. The problem is, I have a sneaky suspicion that most people will sometimes flirt with someone online, simply because they’re there, popping up on Chat.

Who cares that it’s 1am? I’m bored, and I can’t sleep. Or maybe I’ve had an Ugly Day, and therefore message that guy who always responds, hoping he’ll massage my flagging ego. Anyway, what’s wrong with a little light flirting?

It’s ok, right, even when you’re in a relationship? The problem comes if – horror of horrors – you find your lover’s flirtations in full Facebook Technicolour. Then it becomes absolutely not ok. Mine are fine – I am, after all, in control of those, and I certainly don’t mean anything by them.

But his? Ouch. So, if a flirtation falls in the middle of Facebook, and no one’s around to read, does it really matter?

I recently asked a male friend what he thought. “I wouldn’t do anything I didn’t want my girlfriend to do” was his diplomatic reply.

I have since become paranoid that this friend is trying to sleep with me, because, as nice as his sentiment is, it can’t possibly be true, can it?

I once said to a boyfriend: “To test whether an interaction with another girl is cool or not, imagine if I read the messages, would I be upset?” This was a ridiculous piece of advice, since, at that time of my life (I was 20) if he so much as nodded at another girl in the street, I’d instantly imagine they were about to sneak round the corner to have frantic sex up against the industrial bins.

Happily, that desperately insecure period of my life is over, as you can obviously tell. But it’s been replaced by something far worse.

As a late twenty-something, the people I date are genuine contenders for Happily Ever After. I may have a more mature, rational, response, but there’s also more at stake: this could be my future husband wilfully cyber cheating. How bloody dare he (do that to me and the kids)?

Perhaps cyber flirting is healthy; it reminds us we’re still attractive, a good thing to bring back into a relationship. But is it also a bit like porn – the more you watch (so I’ve been told) the more you want. And you want it harder and more explicit each time (I imagine).

I think it comes down to a need for attention: we all want someone to reassure us that we’re sexy. But it’s hurtful to know that someone you care about is purposefully seeking attention elsewhere. The test has to be what my friend advised: if I wouldn’t want them to do it, I won’t do it.

In the meantime: stay away from your partner’s Facebook. Chances are that anything spied will be taken woefully out of context. I once (yes, aged 20) made the error of checking a boyfriend’s phone, and promised myself to never do it again. Not because of any moral fibre, but because it was the most frustrating encounter of my life – I couldn’t confront him about what I’d seen, simply because he would have correctly argued that I shouldn’t have been looking.

Damn.