Are you seriously asking this? Ragini is doing this because she is a goddamn psychopath. And you'll see forums where Ragini fans will be blaming Lakshya for turning her into this... and also wishing for RagYa to happen.
I agree whatever Lakshya did was bad. But trying to kill your sister... thrice? Really. Ragini knows that Lakshya can not love her because he loves swara, Kill swara and he'll come running into her arms. That is what she thinks. She can't see that swara is a goddamn idiot who LOVES HER AND ONLY HER and will happily get back stabbed again and again coz Ragini uski 'behan' hai. She is a PSYCHOPATH who should have been in jail for all the plotting.Or maybe an asylum.
I totally agree with you...
Sometimes forgiving grave mistakes r not good
If you really love her... Show her the correct path... Else she will keep taking u for granted