So whilst you are getting cosy over the candlelight and wine, take a deep breath and agree your six tips to unmarried bliss to avoid arguments and misunderstandings that can so easily rock the steadiest of relationships. The chances are that once agreed you will be less likely to split up and more likely to enjoy a long and happy relationship because you both know where you stand:

1. Agree what you are each going to pay for and how. Separate items into categories such as: general expenditure (e.g. food, petrol, bills that relate to the occupation of the property etc); mortgage and rent; bills that relate to the ownership of the property (e.g. council tax and buildings insurance). It may be that you decide it is only fair to split the costs of the general expenditure, but if one of you has a larger share of ownership in your property you might consider it fairer to split the bills accordingly (e.g. 30:70 or 60:40 as appropriate).

Consider also how you will operate the bank accounts that will pay for these items as this can be crucial to the question of ownership at the end of the day. If you plan to keep your own separate accounts, make it clear that those bills you pay will come from them. Where you plan to have a joint account, agree the amounts you will both contribute and be strict about the items that can be paid from it - if you don’t and you buy large items from it, you could find that you have problems agreeing who is to have the item in the event of a split (and the law on this can be quite complex).

Be careful about credit cards! Nothing can start an argument like one person accusing another of overspending on a joint credit card. Don’t go there. Either keep separate cards or if you decide to have a joint one make sure it is only used for joint purchases and is paid for jointly (and if you do separate, that you agree in advance as to how you will divide these items up - most lawyers advise their clients to toss coins!)

2. Make a cohabitation agreement. Once you have sorted out all of these issues between you, make a cohabitation agreement. You can use a draft such as that found in Lawpack’s Cohabitation Agreement Form Pack and you need never argue about those matters again!

3. Be clear who owns the property. If you are buying a property together you must be clear with each other how you are going to own it and what you will each contribute. For instance, if one of you puts down 70% of the deposit you may agree it is fair that they retain a 70% interest in the property but only if they then pay 70% of the mortgage each month. Whatever figures you agree make sure that the ownership you want is recorded properly by your conveyancing solicitor who purchases the property on your behalf as tenants in common. If he does not do this then you will own the property as joint tenants which means it is owned in equal shares and if one of you dies the share of the deceased will pass automatically to the surviving partner - not to the deceased’s family or anyone else they may choose to nominate in their will. Also, ask your solicitor to draft a Trust deed to reflect the agreement you have reached as to what should happen if you separate since this will then make the terms of ownership absolutely binding upon you both and will cut out any arguments (and huge legal bills) if the unthinkable ever happens.

4. Enter into a Living Together agreement to reflect all you have agreed about the way in which you will live together – what will be the roles you will each have with each other’s children, what are your goals together and how will you divide the everyday household tasks between you. Unmarried Couples and the Law has a simple example for you to use and adapt for your own purposes.

5. Prepare wills together which reflect what you wish to happen to your assets when you die - they are not costly and it is easy to prepare a short will using a kit such as the Lawpack DIY Will kit. Not only do they make things clear between the two of you, but also to your respective families - the worst legacy anyone can leave their loved ones is a dispute over their estate when they are gone.

6. Prepare living wills making it clear at what stage of illness you would like a life support machine to be turned off and what you wish to happen to your body. Don’t leave such decisions to the ones you love - it isn’t fair and it is so simple to prepare one using Lawpack's Living Will Form Pack

Philippa Pearson is a leading Family Law solicitor and mediator who is a consultant with the niche firm, Family Law in Practice who are based in Covent Garden. She is the author of several books on divorce and cohabitation including Lawpack's Unmarried Couples and the Law and the Separation and Divorce kit and frequently appears in the media to talk about family law issues.