Suchitra is not a bad person. She's just easily capable of being brain-washed.
As long as Rajnath and Sakshi are good to her, give her responsibilities and talk well of her husband, she is sure that they mean well for her family. They don't really ask many favours from her, so when they do, she grants it thinking that they can't possibly be wrong!
Unfortunately for her, Dev doesn't think the same way. He'd rather see solid proof than believe what everyone around him seems to be saying. The only disadvantage in his character is that he is emotionally attached to his mother. That's why he was unable to refuse her when she told him to remain back in USA. The only change now is that his guilt is weighing him down, surpassing his usual thinking. 😊