KRPKAB promos are just a message, not the actual scenes, so i believe its already shown, Dev breaking up with Sona, and then stalking here every night, and earlier Sona telling Dev after the family picture fiasco that he needs to have patience, doesnt it depicts the initial promos.
If assuming Dev do not meet Sona as per promise and Sona breaks up with Rithwik, and then both continuing with their lives, without any commitment to each other, then how will the story continue, cause even now Ishwari thinks everything is ok, infact she doesnt want to get her son married also.Sona can wait all her life, but wat is she waiting for, cause Dev is never going to do or tell anything to is mother.I think Dev has to do something drastic to himself, like accident or something to give a reality check to Ishwari, then Ishwari brings back Sona for her son unwillingly, with Mamaji and maybe also Neha advise, Dev and Sona get married, then story on how Dev handles both.