RSRH –
What you don’t realize is, is the fact that no one is interested in allowing two roommates to file their taxes together, it’s only if they are engaged in sinful acts are they interested in equating their deeds to a holy marrital bind.
By all means propose a law allowing any two individuals to file joint taxes, whether they’re two roomamtes, mother and son, brother and sister, etc., but don’t create special rules for individuals doing sinful acts.