Shobna Gulati's character will fear that Karl is cheating on her when he starts disappearing without explanation, according to the Daily Star. Sunita and Karl began an affair earlier this year.
Rovers Return landlady Stella (Michelle Collins) will apparently encourage Sunita to kick Karl (John Michie) out of her home, saying: "I was with Karl for a very long time. Looking back now I don't know how I did it, I really don't.
"I must have been out of my mind to forgive him for all the excuses and lies. A leopard never changes his spots."
Stella will apparently warn Sunita not to "waste years of [her] life" on Karl as she did, suggesting that she will regret it and adding: "Don't let him take advantage of you, kick him out."
"Karl has got away with his bad boy behaviour for too long. He thinks he's got Sunita wrapped around his little finger," claimed a show insider.
"But he won't expect his new girlfriend to team up with his ex. He's not going to know what's hit him."
Gulati is to leave Coronation Street next year in order to spend more time on projects including her own comedy writing.