well, tanya was ansh friend... Ansh was using her to break karan n nandini's friendship... zey succeed in doing zat n zen nandini marry ansh in finkng zat karan love tanya... meanwhile tanya fall in love wiz karan n turn to good... she started to help karan n nandini... as she knw very well zat karan love only nandini.... she supported nandini during her divorce n thnx to her zat nandini was able to divorce ansh n marry karan... wen need gve birth to bhoomi, she went in coma... z family inclu tulsi force karan to marry tanya for bhoomi's sake but still karan was nat able to gve tanya zat love... finally, one nite zey consumate n manthan was z results...
Tanya cme to knw zat she's pregnant onz same d wen nandini come out from coma...
nandini went jail after killing aditya... but 14 yrs later she left karan... karan blame tanya 4 zat...