You think you can, like many do, live in marriage that bores you without showing any symptoms to your children. You can continue to be good, supportive parents together while no longer having interest in each other. If that's you then you need to think seriously about whether you're really prepared to make that sacrifice and how long for: forever or until they reach a certain age? What age will it affect them least?
The most surprising thing I learned in researching my book, It's No Big Deal Really, is that it's better not to make the sacrifice at all unless you can make it forever. The older the "children" are (including adults in their 20s and 30s), the worse it seems to affect them.
If your children are under two years old then you can assume that they'll not remember this time in their lives and they're likely to quickly settle into new routines. On the downside it means that they will never experience having both their parents together and will grow up with the uncertainty of how they fit into whatever new family is created. These children also suffer most from never growing up in an intact household.
Even if they're unaware of what's happening babies will pick up on tension in the house so may be much more restless than normal. Their progression may seem to halt a little; e.g., refusing solid food after they're weaned. They'll therefore need lots of cuddles and reassurance and, like you would with older children, try not to let them hear you fight.
As a toddler's vocabulary develops they will understand the fights between you. They will also have some concept what a fight is and what anger is. They will be very familiar with how angry they are during a tantrum and the fact it passes. Speak to them and reassure them in a language they understand. "You get really mad with Mummy sometimes but you don't always feel like that, do you? Mummy and daddy feel like that sometimes with each other; but that doesn't make it something that you need to be scared of, does it?' Like babies, they will probably show that they're unsettled by becoming more irritable, tantrums may increase and they could revert to more baby-like behavior.
The separation will affect them more than the divorce, as they won't understand the finality of divorce; what will matter to them is if one of their beloved parents is not at home any more. However, like babies, they will soon settle into new routine.
At this age they will need reassurance that they will have the love and protection they need whatever happens, and that they're not going to lose one of you. A few days in a very young child's life is a long time so unless there is a danger that they will hear something try to delay telling them about the separation until the practical arrangements are being made. However if one child is older it would be unfair to expect him or her to keep the secret from younger siblings.
It's worth letting your children's teacher know about the problems at home. It's not uncommon for children to restrain themselves at home (for fear of redirecting the anger they sense to them) and to release that emotion at school in behavior such as bullying. If the teachers are aware they can ensure that they keep alert to possible problems and deal particularly sensitively to minor infringements of rules, e.g., if you've just told your child that you're separating and they forget their homework the next day a punishment is unfair.
Even at this age you're unlikely to be the first parents to separate. If possible see if you can arrange play dates with children whose parents seem to have split amicably. As adults we tend to seek support from others who've experienced the same problems. Children will also find comfort in being able to express their worries to someone who's been through it and come out the other side without the world ending.
It's now been established that, due to the brain's efforts to change a child into an adult, teenagers are much less able to empathize with people during puberty than either younger children or adults. They will consequently make your life tough even if you have a loving, supportive partner; if you have struggles of your own, your house could quickly turn into a war zone.
Teenagers tend to think that they are the center of the world so they assume, even more than younger children that the problem their parents have are about them in some way. They may have the attitude that parents don't have "right' to separate and try to make you feel very guilty about how selfish you are. They may even suggest that you're doing it just to upset them (seriously!). Teenagers like to think that they have the monopoly on being upset and bad-tempered so they probably don't have a lot of sympathy to spare for you. The only way to deal with problems in your marriage when you have teenagers is to keep as united up front as possible or, very quickly, teenagers will play one of you off against each other, which will make your life hell.
Despite the "cool' or aggressive appearance, teenagers can be as scared and upset as younger children. Try to give them a lot of attention, however much you think they don't want it, and sit down as often as you can to talk to them seriously about what's happening. As you come to decisions, involve them and let them have some say. Teenagers think they're adults so the one thing guaranteed to make them mad is if you decide things for them.
I've found that teenagers need much more affection, attention and demonstration that they're loved than toddlers. They'll say they don't want it, and don't need you, but they are the most isolated age group in many ways. As a child we get all the time from our parents, as adults we have our partner to hug, but teenagers are too cool to admit to needing affection. So try lots of hugs in private (when no one else, not even a sibling, is around). If they really don't accept a hug give them affection in other ways. Praise (honest and not over the top) and lots of attention will go a long way to helping them cope.
Teenagers can surprise you: some will not be bothered by your separation, they've seen it all before, and they don't really think it will affect them. Double-check that they really do feel like this, then be grateful and don't try to force them to be unhappy about it.
This article has been edited and excerpted from the book It's No Big Deal Really, permission by Anne Cantelo. Copyright © 2007. It's No Big Deal Really is a parent's guide to making divorce easy for children, and is recommended by the NSPCC.