Nainggolan is currently on a season-long loan at Cagliari from Inter, where he was exiled from the team following the appointment of Antonio Conte as manager in the summer of 2019.
The 31-year-old ex-Belgium international spent four successful years in Rome but following the appointment of former Roma boss Luciano Spalletti as Inter manager, Nainggolan left for the San Siro.
Spalletti was sacked as Inter manager at the end of Nainggolan’s first season in Milan, leading to a loss of his place in the team.
“I don’t want to take anything away from Inter fans, but if you asked me if I was happier to have joined Inter or sadder to have left Roma, I’ll tell you that I was sadder to have left,” he said during an Instagram Live broadcast.
“As for whether I’d return to Roma, yes I would. If the conditions are right, I’d go back.
“I experienced beautiful years with them. It’s a club that loves me, that I love and to which I’ve given everything.
“I miss everything about Roma. I recently watched back the game against Barcelona and, when I heard the [club’s] anthem, I wrote a lot of things to the group. It was still giving me chills.
“Things were so natural for me at Roma that I miss it all. These things all happened with them, so we’ll see. The door is always open.”