Society today is very different to a time when marriage was for life and the idea of a couple 'living in sin' was... well... frowned upon to say the least. Here are the statistics for today.
Statistically in a group of 10 people;
Two to three will have had either 2 or 3 defacto type relationships. One or two will have had 3 or more. FIVE will be heading for there first split!
So with this in mind it could be a very costly exercise to have the potential of 3 or more costly settlements. However if you and your (ex) partner can decide amicably then it doesn't need to be drawn out and expensive.
Here are some legal aspects to what defines 'separation'. The Family Law Act states a separated couple as;