well he said that she was his true love ...and he and her used to engage in some love talks..and he destroyed Mauli and abandoned his unborn child for her...so it better have been deep love and not just him lusting again..tbh I couldn't stand watching Kunal and nAndus scenes ...so I cant give any details about the scenes
Not sure about this though. When did Kunal show deep connection with Nandini ?
He aimed for the bed quite soon with Nandini. After that it was more of bechari Nandini and zaalim zamana and his obsession to protect a damsel in distress.
Offcourse Nandini did satisfy his obsession for food and pampering him. Even though Mauli uthaoed his nakhras as she said once , Nandini uthaoed his nakhras more.