Hello. Welcome to the forum.
It is impled that Atharv is Madhav'e father. It happened in Manali when Vivi and Atharv went to save Ravish before the leap.
Vivi married Ravish because she thought Atharv had left her because he thought she loved Ravish. But this wasn't the case. he left her because he thought he was dying but this was planned by Suman.
Suman hates Atharv because he is the son of her husband's firts wife and she wants Vividha to stay married to her son Ravish.