If you're interested in that area, and would like to encourage the government not to put too many additional barriers in the way of bringing families together (family values, right?), then it's worth completing the consultation if you have time.
The first question is complex enough in itself. From the consultation document, emphasis mine:
2.8 Migration based on marriage or partnership must be based on a genuine and continuing relationship, freely entered into by both parties. It must not be based on a marriage or partnership of convenience, entered into in an attempt to gain immigration advantage. And it must not involve coercion.
This seems all very well, but the problem that arises is what does "genuine and continuing" actually mean, beyond an "I'll know it when I see it" definition that varies depending on the views of the immigration officer in question. In practice there's a risk that relationships sufficiently different to a "default" relationship will be excluded, depending to at least some extent on the privilege and heterocentrism of the immigration officer.
So, it's understandable that the government wants to have a more formal definition1 of "genuine and continuing", and there would be benefits in the transparency of the process if they did - but of course I don't really trust them to get the definition right2.
The current rules significantly privilege people who are either married or in a civil partnership, or intend to do so in the UK. Coming to the UK to live together but not marry or enter a civil partnership is more difficult.
Existing marriages and civil partnerships are taken into account - but of course, there are relatively few countries where same-sex marriages are allowed at all, and many of those are inside the EU anyway.
If the applicants are not civil partners or married (or intending to become such), then they must have lived together "in a relationship akin to marriage" for at least two years, already in the UK.
"Akin to marriage" is an interesting term. In practice, it implies an exclusive monogamous relationship. Again, this gives an unusual inconsistency - someone could be in a poly relationship and able to sponsor a partner to whom they were married but who had been outside the country for years to come to the UK, but not a partner to whom they were not married but had spent several years living with in the UK.
A codification of the existing rougher standards would be very problematic. On the other hand, a codification of a broader standard could be very useful to families wishing to move to the UK.
The first consultation question asks how they could go about making a written standard for "genuine and continuing" relationships. I wasn't able to suggest an answer to that - how do you write a standard that isn't exclusionary? - but I did recommend some areas not to include in the definition, and that if they did make a definition, that was itself put to further consultation.
1 This of course doesn't just affect migration - if the codification of a definition of "genuine and continuing" appears "successful" to the government when used there, it may well be extended to other areas of government work.
2 And in the current anti-immigration political climate, they have quite a bit of incentive to get it wrong.