That's what Facebook's for

Facebook is a useful tool in finding – and keeping – real pals, writes Lesley Thomas

You'd think that the notion of "toxic friends" and "passive aggressive" pals could only be taken seriously among over-analysed American professional classes, but flick through any British glossy magazine or listen to a group of grown women after a glass or two of wine, and you'll soon find evidence Over Here.

Our friendships now undergo as much neurotic examination as our romantic partnerships.

Recently, a friend, let's call her Charmaine, complained to me that she was thinking of "sacking" a girl we both know from her social life. "It's been building up for a while," she said. "I have known Amanda for five years and I have realised that she is not serving my growth in any way."

When I realised she wasn't joking, I wondered whether I'd done enough to have a positive impact on Charmaine's personal development in the decade we have been friends.

Had I known there was to be a reckoning, I might have tried a little harder.

Exhaustion and time poverty have led to a ruthlessness in our social lives. We must protect our most precious personal resources and be constantly on the look out for time-wasters and energy-sappers.

Experts in women's magazines tell us about the Five Friends Every Woman Should Have – the historical friend, the shoulder to cry on, the party partner and so on.

We are encouraged to mull over big issues, such as What to do When Your Best Friend has a Baby, or Is your Friend Stealing Your Style/Making you Fat?

Modern, female friendships are becoming a rather twisted business. Instead of just having a handful of people whom we like and see when we can, our friends must be fit for purpose.

I know single women who have "pulling partners", friends with whom they have little in common other than their desire to find a mate – ideally, they have divergent tastes in men.

It's a logical solution to manhunting when your real buddies are married, but it seems more a transaction than a friendship.

Middle-class Londoners have school-mum friends and NCT Friends, whom they met at the ante-natal classes run by the National Childbirth Trust and stayed in touch.

But even parenting has become a competitive business and we must be on our guard for signs of draining one-upmumship in these associations.

Some have friends they don't even like.

With so many women bringing home at least half the bacon, we compete with each other in the workplace.

Men have always done this, of course, but it is rare that they feel the need to be liked and even pally with their professional rivals, as females so often do. Then there are the "frenemies".

I bumped into one of these in the supermarket the other morning. We have known one another for years and have several bona fide friends in common. I was dressed in my school-run/working-from-home uniform of trackie bottoms and Weetabix-stained sweatshirt and hid in aisle 22 when I saw her.

She found me in the bakery section and we performed surprised delight and embraced. "I can't wait to have children," was her smiling, parting shot. "It must be so relaxing to feel able to walk around looking like that."

Technology seems a helpful solution to the insufficient number of hours in the day.

Emails, texts and social-networking sites make it easy to stay in touch with those we genuinely like, but can't find the time to see.

They also, however, make it too easy to be friends with people we can take or leave.

It's not uncommon or extreme for Facebook users to have more than 100 online muckers.

Since the unspoken ground rule of a Facebook friendship is that it is far from intimate, we're collecting undemanding e-friends with abandon while striking off poor performers in real life.

Perhaps we do need New York style shrinks in Britain.

We need someone to talk to about the state of modern friendship. Hang on, isn't that what friends are for?