WHEN contemplating my singlehood, I sometimes bemoan the fact that some of my best female friends are already hitched, and I wonder what could have been if I had met them earlier.

Not any more, for now I've learnt what it could have been: painful.

The odd thing is that some of these girls (hey, I still love you all very much) seem to turn into entirely different creatures when they are around their boyfriends or husbands.

Around good friends, they are jovial, caring and lots of fun to be with. Yet around their significant other, they unleash strange - and unpleasant - sides I have never seen before.

My first experience was with a Taiwanese girl whom I met while I was working in the United States four years ago.

With her lanky frame, geek-chic glasses and cool demeanour, she exuded a kooky charm that reminded me of the actress Uma Thurman. We hit it off and spent a lot of time hanging out.

When my four-month work stint ended, I visited her in Taiwan.

I met her boyfriend on the third day. That was also when I witnessed her turn from Uma Thurman in The Truth About Cats And Dogs to Uma Thurman in Kill Bill.

It started when we were going for dinner. The poor fellow showed up 15 minutes late while we were waiting for him at a subway station.

When she spied him arriving out of the corner of her eye, a scowl appeared on her face. We were discussing Taiwanese street snacks before that but it looked like she was ready to eat him instead.

He repeatedly apologised for being late - once to me (which was good enough) and maybe like 100 times to her (which was anything but good enough).

'Why are you late?' she snapped at him in Mandarin.

He mumbled something about picking up some items, in a tone so fearful and soft I had to check if Uma had sliced off his tongue with her Hattori Hanzo sword.

'That's not an excuse,' she replied coldly, before pulling my hand and walking off in a huff.

For at least the next 10 minutes, I was walking (uncomfortably, I must say) next to her while he trailed three steps behind to atone for his 15 minutes of shame.

I suppose this isn't entirely horrible, considering that he was in the wrong, after all. Maybe she was a real stickler for punctuality. Maybe when they were high-school sweethearts, he'd been late and had made her miss the first five minutes of Titanic.

So okay, maybe this was understandable, although rather scary to me.

But then I had another experience with a friend who has been married for four years.

This time, the poor chap didn't even do anything wrong.

At a party she threw at her house, a group of us were just settling down for dinner. We didn't really know her husband so he was left to do his own thing while we gathered around to eat.

After a while, he must have thought: 'Hmmm... I shouldn't be so unfriendly. These people are in my home. Maybe I should go over and talk to them.'

Bad move, pal.

He came up to us while we were having drinks and I think he might have made some comment about the food.

I can't remember exact details because they were completely overshadowed by my friend's reaction.

After breathing a heavy sigh, she rebuked in a stern voice: 'Yah, whatever lah. Not funny.'

He was about to open his mouth to say something when she continued: 'Go and read your book, lah.'

Now any man will tell you that if you're going to put him down like that in front of all your friends, you might as well just take out your whip and start flogging him.

And this coming from a woman whom I've almost never seen without a smile on her face.

Incredibly, the first person to wipe it off so quickly was the man she had promised to be with through sickness and health for the rest of her life.

A few uncomfortable seconds passed. Then I think I heard a whimper as he retreated to his bedroom.

I've been trying to understand this schizophrenic, Jekyll-and-Hyde, Autobot-transforming-into-Decepticon kind of behaviour from otherwise perfectly wonderful women, but I'm not sure there's a really rational one.

It's possible, I suppose, that familiarity breeds contempt. When you have been together for a while, whatever sweet quirks your other half has may morph into irritating habits that bring out the worst in you.

My Taiwanese friend had a different take.

A few days after that incident, I asked her if she was always so difficult with her boyfriend (there were a few more incidents subsequently which can fill a couple more columns).

'Yah of course I have to be tough with him. He's the one who will be taking care of me for the rest of my life. I can't apply the same standards I do with my friends,' she said.

Perhaps she has a point - as long as you don't push it too hard. Last I heard, the two were no longer together.

Yet, I can't help but wonder: Doesn't it make more sense to treat the love of your life better than your friends?

As for me, I doubt I'll think about what could have been with my female pals any more. At least, not until I have met them in the company of their boyfriends.