“Who said that “Bashert” and successful marriage are one and the same? What if it is Bashert for your marriage not to be succesful? Or if you marry someone not bashert (zivug sheni, for arguments sake)?”
“Bashert” means something after only one dies ,then one could say it was “Bashert”
Or
as
R’ Yaakov Kamenetzky said “Bashert” in English means you like each other very much