The reason for this is to improve the rights of the vulnerable within the situation of a cohabiting couple splitting up – either a partner or a child could be vulnerable.
However, a side affect is that this change in the law would be legislating against casual, no commitments, cohabitation. Bear in mind that most of the time cohabitation is the free choice of the cohabitees – no one is being coerced into it (there are unfortunately exceptions, perhaps those are the examples we should be concerned about?), so to imply that current cohabitation is criminal and that it should only ever be accompanied by extended commitments and rights isn’t necessarily something that we should do. Basically this would be legislation to restrict people’s freedom to cohabit in an attempt to protect people who are often putting themselves in a vulnerable position out of free choice.
for example) I don’t believe that it is the role of Christians to impose laws on wider society.
Please don’t think that I’m saying we shouldn’t do whatever we can to help the vulnerable, including children, but I’m not sure that our ‘help’ should be to impose legal restriction on people based on our conception of morality.