I think (I probably have too much logic for ITV world) Rhea got tired of Ahaan showing affection towards her. Went into depression mode and went back to her former boy friend or whoever. That guy might be blackmailing for money and even though they look rich, they might not be. So, she needs Ahaan's bank balance very badly and very quickly. That is the only thing that is making sense.
I had another thought that she might have let someone influence her in investing in fraud stocks and lost a lot of money, but then she never showed any aptitude for taking charge or business, so I doubt she ever did any work let alone make such decisions.
Whatever it is, I hope she is not pregnant, cannot handle one more story line where FL is hell bent on proving that the baby is not the ML's. That is shitty story line.