Livre d'Or

I think there are two main issues here - societal and monetary. It would be nice if all relationships did not have value judgements applied to them, but like it or not many people do have a hierarchy of relationships (possibly including myself; whilst on the one hand I'd try to assess things on their own merits, on the other hand if there are two simultaneous demands on your time there is by definition a hierarchy). There is quite possibly the reasoning to provide minimum standards that apply to all : most people help their immediate family in times of need; you can't have work etc denying this as it would then have to be applied regardless of position.

The economic position is slowly improving but generally applies to state recognised partnerships. In cases of marriage and civil partnerships there have to be mechanisms to recognise serious commitment, usually by making it difficult to dissolve that partnership. For other types of relationship there's probably a long way to go legally!

I'd also note that as a single person with good friends, that tends to lean towards monogamy as a serious relationship model, whilst I have some decent support from friends and family I tend to think for more guaranteed support it's likely to come from someone I'm in a commited relationship with, or from myself, rather than any other source.