I believe Shiv/Vyom played with Sharanya's Life and have harmed her / tortured her mentally and physcially. Poor Girl, she didn't know what was happening behind her back. Now, Shiv/Vyom want to prove that they are Innocent when they were NOT EARLIER.
I don't think Sharanya killed Cycle Boy. CYCLE BOY KILLED SHARANYA AND MADE HER GO INTO AMNESIA BY SCARING HER, MAKING HER GO INTO COME & TRAUMATIZING HER STILL. Luckily, Sharanya is a Strong Girl with Divine Blessings so she is fighting back with the Strength given by Divine Mother. SHARANYA SHOULD NOT MARRY EITHER SHIV OR VYOM.
I believe Shiv/ Vyom might have tried to KILL Sharanya's Father according to one of the promos because we see Shiv/Vyom as Obsessive Freaks.