I am not sure if anannya's condition will be a reason because lets face it its a BT show where vilan's truth does not come out till the end and sometimes not even at the end (case in point KDMHMD's Veera and Gyatri) so i don't think Ritesh's truth will come out even after the leap till they loose every single thing. I feel Ritesh will be the one who will surely have a hand in Onu ending up in asylum. Like may be Onu went into shock or something after he realized that he made a mistake and lost Taani forever and instead of getting him the medical attention needed, Ritesh might have him declared as mad because don't forget Onu is Shehkar's elder son who will take over the business so Ritesh would surely want Onu out of the way.