It's a trend that cannot be separated from shifting gender roles. It's significant that Simone de Beauvoir, the mother of modern feminism, refused to live with her life-long partner Jean-Paul Sartre. Sharing a home is a different ballgame for women. Trained to nurture and mould to a man, a woman's identity can easily become subsumed by her partner's, her earnings may well not match his and, according to the latest OPCS (Office of Population, Census and Surveys) statistics, she will certainly end up doing most of the cooking.
We live in a time of change with far more lifestyle choices open to us than ever before. But it's hard to ask the question whether to live together or not when the subtext is "if you loved me, you'd move in with me". A person resisting live-in romance risks being labelled a "commitment- phobe", a sad individual whose unconscious fears are standing in the way of a normal relationship.
Is it true that you can't be truly committed if you don't share a nest? According to Dr Maryon Tysoe, a social psychologist and author of The Good Relationship Guide (Piatkus pounds 7.95):"No research has been done on this point." But many people none the less have strong opinions on the subject. Denise Knowles, spokeswoman for Relate, the counselling charity, asserts that: "Couples who are in a long-term, monogamous relationship but who won't take that final step to living together shouldn't kid themselves that they are committed. They haven't put their relationship to the test".
Malcolm Stern, author of The Courage to Love (to be published by Piatkus in September) agrees: "By living apart you stay on honeymoon - you don't have to deal with the dross and disillusionment which is part of a real relationship. Before you can build a paradise on earth, you need to fall from the Garden of Eden."
But it's hard to believe that living together automatically equals commitment when more than four in 10 marriages are likely to end in divorce. "Couples can be together for years and have children and tragically have lost their commitment," says Dr Tysoe. "Commitment has been defined as wanting your love to continue for ever. Who is to say that couples living apart aren't doing that?"
Dr Chris Johnstone, an addictions specialist, adds: "Sometimes couples living together avoid difficulties by retreating into overwork, the pub or affairs. While cohabitation may be one measure of commitment, having the courage to communicate, and to face difficult issues together is another. If you had to choose, wouldn't you rather share the same relationship than the same house?"
Glen and Julia: `Relationships are like a fire - too near and you burn'
"If I'd put pressure on Glen to move in with me, the relationship would have crashed," says Julia, 39. A freelance publicist and trainee counsellor, Julia has three young children from a previous marriage. "When we fell in love, Glen was ready to sign up as a lifelong partner but was ambivalent about becoming a parent - being a daddy has never been on his agenda. I'd been married twice and was struggling to `find myself' - I wasn't looking for a live-in partner."
Glen, a 34-year-old doctor, is happy with the situation: "To have moved in would have felt like living in a pressure-cooker. Once I was sure that I was not expected to live in, my heart opened and I really felt able to commit myself."
The couple see their partnership as one for life. "I feel incredibly lucky that I've found a relationship which has the stability of a marriage but which enables me to find my independence," says Julia. "I love my home," says Glen, "and I'm secure in a loving relationship. I don't feel restless or lonely any more. I can really enjoy being on my own. I have a demanding job and I need peace and quiet to recharge my batteries. I've seen couples split up because they haven't had enough room to be alone. Having our own homes, we don't crowd each other out."
Glen and Julia speak on the telephone every day, drop by each other's houses several times a week and spend two nights a week at Julia's house. Living apart means time together can be bitty. "My feelings about this are mixed," says Julia. "On the one hand, time spent with Glen is too short and precious, and I feel forlorn when we part. On the other hand, I can devote my energies to my family and myself, and I love to sleep alone."
There are no set times when they meet and each time they negotiate, there's a possibility of friction. "A `no' can feel like a rejection," says Julia. If he's busy or something, I can get hurt and bitter, which in turn can make Glen feel hemmed in, as if he can never do enough for me. But I had similar problems when I was married, so I know that this can happen even when you are living together. For me, the constant coupledom of marriage masked the real issue, which is a massive insecurity inside me. I need to live alone so I can tackle this and it's marvellous to have Glen's support while I do so."
Glen feels that weathering the difficulties of living apart has given the relationship firmer foundations. "We get on well and have fun, so there's a lot of readiness to try to find a solution. We talk a lot; some couples couldn't bear the amount of communication we have. We both hate conflict but it's inevitable, and knowing we have resolved some very tricky moments has helped deepen the relationship.
"Relationships are like a fire," he adds. "If you are too far away, you freeze; too near and you burn. You need to be near enough to be warm and that's what we've got. I'm in a sustainable relationship with a woman I adore. I want it to endure and by living apart, I think we are allowing it to thrive."
Mick and Sophie: `Our time together is so precious'
Mick and Sophie, both 34, have just celebrated four years of being together - and the last three years living apart. "Mick moved in with me soon after we met," says Sophie, an award-winning designer. "We couldn't keep our hands off each other, it was like a drug.
"But Mick has mood swings and I get infected by them. Although he tried to reassure me that they weren't my fault, my insides would feel ripped out. It was like living on a roller coaster."
It was Sophie's suggestion that they live apart, an idea Mick, a cabinet maker, resisted. "I felt rejected," he says. "I thought it meant that she didn't value our relationship or want it to last. But it was her flat and I didn't want to piss her off; I moved out."
"I felt wicked kicking out my man and it was horrible separating out our possessions and clothes," says Sophie. "I was terrified that by insisting on my space I was destroying a partnership with a warm and sexy man. But he rang me the first night to say he was making me a box inlaid with stones. I was filled with hope for our future."
"With time I could see for myself that living apart worked better," says Mick. "This house has a woodwork shed which meant that I started work again. I could feel my self-esteem creep back. I felt calmer, less moody and more able to trust that Sophie really did want to be with me."
Liberated from everyday drudgery, is sex is a more exciting affair?
"We're well into the non-glamorous, farting stage now anyway," says Mick. "At first, absence added an urgency and a thrill. The hardest part is getting very close physically and then parting. Both of us can feel quite bereft. So it's important that we don't make love just before we are about to separate."
They still share domestic rituals, like shopping in Sainsbury's and cleaning (and arguing about whose kitchen floor is getting more attention). They sleep together about 4 nights a week.
"The drag is that there is about a 20-minute drive between us and I have to cart all my precious belongings between his place and mine," says Sophie. "It's also harder to socialise because time together is so precious. But there is less to argue about. I'm solvent but Mick isn't and having separate finances means I'm not bugged by his attitude to money, and I don't make him feel inadequate or nagged. I've also regained my psychic space. When Mick was in the house, I couldn't help but tune in and that hampered me creatively." Sophie feels this arrangement could carry on even if she became pregnant. "Two of my best friends are single mothers and they say they do a better job - men have such different ideas about childcare that they can inhibit the mother's intuition. I would want Mick and me to live much nearer, though."
But how can this be called a real relationship if living together causes such difficulties? I can't live without Mick and I can't live with him. I'm sure a lot of people can relate to that," says Sophie. "Four years on and we are still happy and together. Where's the lack of commitment in that?"
together - and apart
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