Straight from the horse's mouth:
Nahar & Antara bachpan ke dost hain..(childhood best friends).. They liked each other alot, and no one could come in between them. Nahar had a flair for painting, but used to make only Antara's paintings...Antara was a beautiful young girl who grew up with Nahar as she was the family servant's daughter. Her favorite color was cream, and nahar has lots of paintings in that "purani dodi" of antara's in white/cream saree in various poses.
One day, someone expresses the desire to get Nahar and Antara married, and family elders object because she comes from a poor servants family.. So they decide to get her forcibly married off to someone else and she commits suicide because of this in Nahars ancestral property. Her father-the old servant goes mad because of this and Nahar and his family were to blame for it. (Thats why tara said that ek bahut bhayanak ghatna is ghar mein bhi hui thi)..and for the sake of family honor, they squashed the issue before it became public and no one ever talks about it.
When saloni finds out about this, she will be horrified because a person was killed, father became mad, and her husband and family are the cause of it. Since she is the satyavadi insaaf ki murti types, she must decide whether she should bring insaaf for the poor girl and her father, which would eventually mean going against her husband and family and the kasme-vaade she made during the saath phere. Does this mean that finally saloni will have to choose between doing what she has always believed in, or surrender to the zanjeer tied in her legs by her saath phere!
Connotations: Antara could have resembled saloni and thats why Nahar wanted to marry her once he set eyes on saloni. Antara's father maybe kept in that "purani dodi" and Nahar must be going there every night to give him food and to make sure that he is ok, and must be doing all this as paschaataap (remorse). Also Anatara-Nahar relationship may explain why Nahar is so freakishly understanding of Neel and Saloni's relationship inspite of knowing that they once liked each other, since he knows what childhood friendship is all about, and has gone through this phase.
P.S: This is my interpretation :-) Please dont kill me for not saying this in the beginning you guys!! :-)
Antara = = Make believe name, Horse = = me!