04/08/2014 10:25 BST | Updated 22/05/2015 06:12 BST

Why Must We Be BFF, No Matter What?

I was party to an enlightening conversation the other day. Over a glass of wine, a woman in her 30s was sharing her woes about a 'friend' who was taking her for granted. They'd known each other since university and had shared good times, but the friendship had become progressively one-sided. As she vented, it was clear she felt she was being mistreated, and was emotionally (and somewhat financially) drained from the relationship.

Well, that happens. Friendships can erode over time if one or both parties don't work at them. But the extraordinary part of the conversation was this:

"Gawwd. So when is she moving in then?"

"Next weekend."

Some people would call her a good friend, one who sticks around No Matter What. I call her a glutton for punishment. She clearly drew only negativity from time spent with her tormentor and even as she sat in that bar, discussing how awful it all was, the terrible 'BFF' was packing up and preparing to move in – at her invitation!

It has always puzzled me a bit why some women take so much crap from their female friends without, you know, dumping them. Why do the sorts of women who would certainly not take any such rubbish from their partner take it from their so called mates? What is it about female friendship, that idea of 'sisterhood' which is born at secondary school (while we're all sharing lipgloss and wearing exactly the same shoes), that makes us, as adults, incapable of ending companionships that have gone bad?

The thought of taking a scythe to the friendship, just cutting her losses and moving on, had not even occurred to that intelligent woman – and it occurred to me that I know several intelligent women who continue to feed relationships that really should be thrown to the dogs. That's what most of us would (at least eventually) do with a romantic relationship that was in tatters.

For some reason, though, the thought of sitting down with a friend and saying: "This just isn't working for me, I think we should stop seeing each other..." seems about as natural as Tara Palmer Tomkinson's pretty new nose. It's just not what we do. Even when women do decide they no longer want to be a doormat, they find it terribly difficult to actually say so bluntly – ironically I've seen some take what's generally considered a bit of a male escape route: ignoring texts and phone calls until the pest gets the message and finally slopes off.

According to the highly unscientific survey I undertook among some women of substance (and some other women too, ha!), culling rubbish friends is great in theory, but longevity is a big factor. If the person in question has been a friend for a long period of time, there's more of a tendency, even an obligation, to stick with it. But then, if you've been friends with someone forever, don't they owe you more too? If they keep letting you down, is it not worse than a relatively new gal pal who does the same thing?

Author Emily Dubberley, who wrote You Must Be My Best Friend Because I Hate You: Friendship and How to Deal With It thinks good friendships that have been neglected deserve to be put back on track, but continuing with those that have run their course, or worse, have become destructive, is pointless. She says: "People do change and sometimes the only thing to do is let go, because there's just too much baggage to move on from."

I can only guess the woman in the pub thinks she is being kind, but she's not. She's not giving her friend the opportunity to amend her attitude; she's certainly not being kind to herself. I don't purport to be an expert in the psychology of friendship or anything, and with my terrible excuse of there never being enough hours in the day, I know sometimes I'm not as good a friend as I could be. I'd like to think, though, that in her situation, having tried my very best and given as much as I could give, I'd be brave enough to whip out the scythe, take that supposed friendship out at the knees and reserve my energy for the people in my life who deserve it.