A quarter of married couples are only together for their children - and plan to split once they grow up, a new study has found.

According to a poll of 2,000 married parents, affairs, growing apart and 'becoming more like friends' are among the top reasons for being unhappy in a relationship,

Yet staying in a bad marriage and putting on a front for the sake of the family could do more harm than good for children, a family lawyer warns.

Many couples are going to great lengths to hide unhappiness for the sake of their children

Many are too worried about the effect a divorce would have on their youngsters to call it quits, according to the research commissioned by law firm Irwin Mitchell.

And almost one in five (19 per cent) are considering staying together over the Christmas period before putting an end to their marriage in January.

But it also emerged that of those who have already divorced a partner, one in four (26.5 per cent) stayed in the relationship longer than they wanted to for the children - and almost eight in ten (78.5 per cent) now regret doing so.

Martin Loxley, head of the Family Law team at Irwin Mitchell solicitors, said: 'We see many couples in relationships where they aren't happy, or don't really want to be in, but who stick together for the sake of their children.

'While it is an understandable reaction for parents to feel that it would be better to stay together to avoid the impact of a relationship breakdown on the children, in some cases doing so may only serve to increase the long term adverse effects on them.

'Children can often pick up on things and regardless of how much of a united front you put on, youngsters, particularly older ones, can sometimes see through it.

Many couples continue to go out on 'fake' date nights to keep up the appearance of wedded bliss

'In some cases, children feel 'cheated' if, when they get older, they realise their parents were putting on a "front" during their childhoods.'

Unhappy couples will mask the problems in their relationship by going on 'date nights', continuing to take family holidays, keep problems bottled up and arguing in another room, away from the children.

Mr Loxley said: 'There is help available to parents to work together to ensure that their children are affected as little as possible by a break-up, allowing all to be happier in the longer term.

'If you are in an unhappy relationship, and if a divorce or separation is handled sensitively by both parents, children can and do prosper more than they might have done, had their parents stuck together, but in an unhappy household.'

Many are too worried about the effect a divorce would have on their children to call it quits

The study found four in ten are currently in a marriage they aren't completely happy with, with more than a third saying they have too much to lose to get divorced.

Many feel trapped by not having the money to live alone, not being able to afford the divorce or wanting more time to make a final decision.

But 37 per cent of married parents admit they have considered asking their other half for a divorce, only to hold off due to concerns about how it would affect their children.

More than a third admitted they have stayed in a marriage longer than they would have liked to save their children any distress, with 21 per cent considered themselves as separated, despite still living with their partner and acting like a couple in front of their offspring.

Researchers also found 18 per cent have a date in mind to end their relationship, but while more than one in five have set this at a couple of months, one in 20 are planning to wait ten years or more before calling it quits.

One in five unhappy parents admitted to waiting until their children reached at least 14 before going ahead with a divorce.

Another one in five intend to see out the Christmas and New Year celebrations as a family before making a decision on whether to call time on their marriage.

And 27 per cent of parents will be making more effort to hide any marital woes over the Christmas period with most planning to keep their problems bottled up rather than discussing them.

Admirably, 42 per cent will make a positive effort to ensure that any arguments take place away from their children or loved ones.

Martin Loxley of Irwin Mitchell added: 'Bringing a relationship to an end is a difficult decision and not one to be rushed.

'We've worked with many parents, all of who want to minimise the impact of divorce or separation on their children.

Top ten things parents do to keep up appearances 1. Keep problems bottled up rather than discussing them 2. Argue in a different room/away from children 3. Enjoy family Christmas and birthdays 4. Sleep in the same bed 5. Go on family holidays 6. Go on family day trips 7. Cuddle up on the sofa to watch TV in front of the children 8. Kiss each other goodbye in the mornings 9. Hold hands 10. Go on date nights Advertisement

Top ten reasons for staying in an unhappy marriage 1. I have too much to lose 2. Worried about the impact on the children 3. I can't afford to move out/live on my own 4. I can't afford to go through a divorce 5. I want to give it some more time before making a final decision 6. Stigma of divorce 7. For my partner's money 8. Worried about how we will manage contact with the children 9. I worry I won't meet anyone else 10. We have too many shared financial interests Advertisement

'For some, this might result in their delaying a date for separation.

'For others, working closely with professionals, including mediators, counsellors and therapists, can help the family to address arrangements constructively and positively.

'There is a wealth of information available to parents - and children (in an age-appropriate way) - to help them come to terms with a huge change and move forward to the next chapter of their lives.

'There are many ways that an amicable separation can be achieved to have a minimal impact on any children involved.

'The most important thing is that both parties are prepared to put their kids first during the process and avoid fighting over issues, as involving children in a tug of love can be extremely upsetting and harmful for them.

'Studies have shown that if parents are not happy their feelings will inevitably affect the whole family no matter how hard they try to hide it.