Randy and Bian had agreed to match Bima and Rasya, but they also left the decision to Bima and Rasya because they would be the ones to go through it, therefore they would not force an arranged marriage between them.
Unfortunately, Rasya was already too obsessed with Bima and considered her match with Bima as an arranged marriage, and she even went to the length that this agreement and arrangement was irrevocable. Rasya loved Bima very much up to the point she was being so much delusional that according to the way she saw it Bima also loved Rasya. She then thought that it was Seruni who teased Bima and used all means necessary to make him turned away from her so that's the reason why she hated Seruni so much.