IF THERE is one thing that never fails to astound me, it is couples who intend to marry without having lived together first.

I hardly ever come across such people - the last occasion was about a year ago, from a good-looking, lively, humorous 20-something lad not long out of university. He was adamant that he did not want to live with his fiancee before they tied the knot.

People like him are rare and, according to research, they are becoming even scarcer.

More than 90 per cent of couples now live together before marriage - and only three per cent have never had sex before their wedding night.

The latter may be of the utmost importance to most couples, but when you are living with someone it is by no means the main source of friction.

Day-to-day habits are likely to spark arguments that can rapidly lead to one or the other storming off to the spare room.

Little things like not putting the lid back on the toothpaste, leaving lights on, dropping dirty laundry on the bedroom floor, and leaving jam-coated knives deeply embedded in the butter every morning.

When two or more people are living under the same roof these somewhat trivial things can quickly turn into issues of mammoth importance.

One person will have "words", and the other will promise to stop. But old habits die hard, and invariably, after a short time things will slide. And there we have the basis for nagging, bickering, more nagging, heated arguments, separate bedrooms.

Living under the same roof is far from easy. It doesn't matter whether you are husband and wife, best friends or students sharing a flat (I remember all sorts of whispering campaigns and heated exchanges in our student house over who was using all the milk and not replacing it, who wasn't pulling their weight over the cleaning and who was guilty of never flushing the toilet).

We all live differently and in any sort of shared accommodation you have to be incredibly easy-going not to get worked up about certain things.

Living as a couple, you grow accustomed to each other's ways and make allowances for them. But even when you have slotted into a routine which is acceptable to you both, there is, as they say, no accounting for taste. Music, food, television.

While you can address each other's irritating habits, you can't change each other's likes and dislikes. I still cringe when I hear the dreadful monotone of David Bowie or the inharmonious din of Jimi Hendrix - two of my husband's favourites - and although I make disparaging comments I know that I have to suffer them, as he tolerates my love of his worst TV nightmare Sex And The City (I watch the late night repeat, on a Wednesday, after he's gone to bed).

I know there will be those who will say it doesn't reflect true commitment, but I believe that living together is a trial for marriage and helps you to decide if you can be happy together.

Having said all this, I may be wrong. Living together might work against you. My parents have been happily married for 44 years and lived with their respective families before their wedding. Had they lived together first, my mum would have found out how prone my dad is to forget to take his shoes off and ferry mud on to a freshly-vacuumed carpet. She may have had second thoughts.

Updated: 08:33 Tuesday, March 09, 2004