Carlos Castro, 65, from Lisbon was found dead in his room at the InterContinental Hotel in New York’s Times Square on Friday evening.
The celebrity chat show host was visiting the city with 20-year-old Renato Seabra, who shot to fame in his native Portugal after appearing on a television reality show.
The couple had travelled to New York to celebrate New Year’s Eve and to take in some Broadway shows, said Luis Pires, editor of the US-based Portuguese language newspaper Luso-Americano and a long-time friend of Mr Castro’s.
He told reporters that the pair had been a couple for several months, but “I think they were a little bit upset with each other, for jealousy reasons.”
The body was discovered at 7pm on Friday after the wife and daughter of Mr Pires told staff at the hotel they were worried about Mr Castro. They had spoken earlier in the day but alerted hotel staff after he failed to meet them.
Police said the victim suffered serious head trauma and his scrotum had been severed, apparently with a broken wine glass.
Mr Seabra was detained by police within hours of the body being discovered after he sought treatment for wrist wounds at St Luke’s Roosevelt hospital.
A spokesman for the New York Police department said on Saturday that Mr Seabra was undergoing psychiatric evaluation at Bellevue Hospital Centre and no charges had been brought. He was described only as “a person of interest in the case”.
Tributes flowed in Portugal for Mr Castro, who was also a newspaper columnist and author of several books, and had won admiration for his bravery in coming out as a gay man.
“He had a kind of a Liberace style,” said Mr Pires. “Eccentric, but very well-known.”
Mr Seabra was a recent finalist on a Portuguese reality show that searches for the next top model.