Mouli is Taani's childhood friend who was always attracted towards Taposh, who is Taani's elder brother. Robindo fell in love with her and their marriage had been fixed as Mouli realised that Taposh didn't harbour any feelings for her and she decided to move on with Robby.
But it was later on revealed that when Robby went to visit Onu in America, he cheated on a friend of Onu's and made her pregnant.
That girl died after giving birth to Robby's child. That child was brought here. That is the baby you see with Jonaki.
When Mouli came to know about this, she refused to marry Robby and asked Taposh to marry her. Taposh, who had by now realised that he loved Mouli, agreed.
So, Robby felt that Taposh snatched Mouli away from him and he wants to make Mouli realise that she made a great mistake by marrying Taposh. Thus to take revenge, he married Jonaki.
Mouli is pregnant with Taposh's child only.
Next time, please use the Tere Liye help desk.😊