I don't think they will get together until Tanya DIES, basically they have never lived together, First she got married to Ansh then when she married Karan, she went in coma for 3 YEARS. After she came back from coma, Karan was never too happy with her because he felt bad for Tanya, and then at the end she ledt him agan.
I don't even think karan really loves her, he just like the idea of loving her.
Nandini is RIGHT for not to come back, I mean twenty years of living with someone, he shouldn't leave Tanya.
I hope Nandini is married to someone, so Karan gets his senses BACK