Apart from the the current track (of Prachi being the mother of Ritwik) which is totally illogical and hence makes the characters also behave quite illogically, can you recollect instances where the characters have done or said things which are quite illogical?
Here are a few I can think of :
1. After the attempted rape, Milsi telling Prachi he had no intention of raping Prachi but just wanted to scare her because he wanted to see the fear in her eyes, just as Alaap had scared Sukruti.
If anything Suki was shamed by Alaap, not frightened of him. Alaap had not raped or attempted rape on her. He was more clever. He duped her into a fake marriage and slept with her. This is not even remotely similar to what Milsi did to Prachi.
2. When Neev asked her to tell the truth about the baby, promising that he will prevent Milsi's arrest (in the smuggling case) Prachi thinks to herself that if she tells him Milsi will be safe but Neev will be sad.
I frankly did not see the logic here. If anything, he will be angry, not sad, that he is taking the blame for Suki's kid, especially since she is Milsi's sister (There is no love lost between him and Milsi). Suki also happens to be his brother's wife so he will be angry that his brother has been kept in the dark.
3. Ayesha telling the polic man who came to arrest Milsi in the arson case that Milsi could not have been in the crime scene since she was with him in a hotel room. She further tells him that he will have to believe her because she cannot be lying as she is Neev's wife and would'nt want her husband's ruin.
Here she seems to contradict herself. If she was with another man(other than her husband) in a hotel room, she obviously was having an affair with him. How can such a woman then want what is best for her husband? Would she not connive with the lover to destroy the husband, thereby proving Milsi was indeed behind the arson?