I don't know about everyone else but I for one, definitely feel, that Sulochana agreed for the bidaai, not bcoz she believed in Manav's love and honesty, but bcoz it was the only option available for her. Archana had already accepted him as her husband, and breaking this relation would only deepen their problems as they wouldn't be able to get another match for Archana (like Purva, her friend's daughter who had to get married to an old man).
The reason I think so is bcoz in the 12th Aug episode, she never once praised or even mentioned Manav's love and honesty (unlike her husband who always said so) Even when she said, "When you 3 sisters would come home to your maayka, I didn't want you to feel bad for not getting a good husband" , or when she said, "Each time you were rejected by a boy, I thought God would send you someone much better, but God got you married to a mechanic...". I thought she would say something about manav, something like, '...but I'm happy you've got a husband who loves you..." Nothing of the sort happened. Her speech rested only with the fact that this was Archu's destiny written by the Gods themselves and so it was best that they should all accept it. Even when she was talking to Archana alone at night, she never mentioned anything about him, or said anything about him, even though she did mention that she would have to change her in laws with her sanskars.