Lupoli will join Fiorentina at the end of this season on a Bosman deal.
Marino said: “I won’t lose any sleep over it. I congratulate Fiorentina on a job well done.
“I had a verbal agreement with Lupoli’s agent. I thought he wanted to come here. But then I heard about the announcement from Fiorentina.
“I hope the player explains his reasons because it would be sad if Napoli fans booed him when he comes to our stadium.”