How can it be triangle when dutta revels that he loves someone else. I feel There are three things that mite happen. May be these are the possibilities they are refering as "TRIANGLE". For dutta it will not be triangle. For Nakusha it might become. Hope she doesnt convince Naku that she is better choice for dutta in his life than naku. Nakusha is bholi... you know.
1) I think Seema will definately turn negative but she wont inform chaskar or anyone. She wants dutta back in her life, she mentioned that she loves him. But she cannot do anything about getting dutta back. she might try to harm him by creating some rift between dutta and naku. May be now she ll want dutta also to be unhappy as she is. Thus she ll betray him again.
2) But LTL sometimes brings such unpredictable twists, it might happen that she never had any good intent to help dutta. It might happen in the end that she was behind him for his money and power. May be she wanted to be with him to have comfortable life ahead. May be therefore she might ve done all this nautanki to win his heart. Now that she's clear that this is not gonna happen, she might now harm him. She might inform his enemies about him. If she couldnt do that in Nakusha's presence then she mite try to harm Naku. Thus she ll betray him again.
3) Or seema has really become positive. And she ll die for dutta in this "LADAI", while saving dutta or nakusha. So Chaskar might kill her. Thus she might die happily.
In all of these cases she has to die now in the end to end her track. Please do it ASAP.