Confusion with Vowing Kemmering

In chapter eight they explain what kemmering is and vowing kemmering. It says that once you vow kemmer you can not vow with anyone else after death or divorce. Does this mean that after your kemmer is gone you can not have relations with anyone else? Is that it for kemmering for that person? I did read in the chapter before this that Estraven had vowed  kemmer and his kemmer died. He then had Ashe as his kemmer. He even bore children with him. He said that their vow was a false vow because it was a second vow but he had still made a vow to Ashe. Are the rules of Karhide starting to bend? I am sure the vow that they spoke of was not known and kept secretive but they still made a vow. They obviousley love eachother and have feelings past kemmering. Where does the boundries of this rule of vowing kemmering lie? The investigator who wrote the field notes in chapter eight had been to Karhide decades before Genry, maybe now the regulations of vowing kimmering are more lose? I know the people of Karhide follow or seem to follow all rules and regulations very closely in fear of being exiled, but are some of the old ways of Karhide starting to become obsolete slowly but surely? Or have the morals behind vowing kemmering never really been followed as much as they say? I am just trying to figure out if a revolution is on its way with vowing kemmering.