> Long-term couples tend to take care of each other's health and wellbeing ... because it makes citizens happier, more productive, less likely to need public handouts ...
Citation needed. Plus, the benefits have to outweigh the costs: tax breaks, unhappy folks (would that cause health issues?) stuck in the bad marriages etc.
I am guessing availability for comparatively stable social unit for raising kids might be a large enough positive, but the benefits should then be for families who raise kids, potentially scaled with the number of kids (don't know if that's already the case). Even the other benefits you mentioned, have nothing to do with marriage - civil unions (or even group of not-romantically-involved-with-each-other friends) can make citizens happier, productive, less likely to need handouts, raise children well (if single parents can, why not multiple parents?) and produce taxable wealth.
Citation needed. Plus, the benefits have to outweigh the costs: tax breaks, unhappy folks (would that cause health issues?) stuck in the bad marriages etc.
I am guessing availability for comparatively stable social unit for raising kids might be a large enough positive, but the benefits should then be for families who raise kids, potentially scaled with the number of kids (don't know if that's already the case). Even the other benefits you mentioned, have nothing to do with marriage - civil unions (or even group of not-romantically-involved-with-each-other friends) can make citizens happier, productive, less likely to need handouts, raise children well (if single parents can, why not multiple parents?) and produce taxable wealth.