You Must No Longer Lie Alone - David and Jonathan, #5

The book chronicles the adventures of two gay couples, David and Jon and Tom and Luke from the earlier books in the series, and introduces a new character, Luke's Italian brother Sandro Mascagnoli. Sandro comes up to St Boniface's College, Camford to study engineering. After an unhappy gay relationship with Jack Meredith, a research student, he meets Dominic Ovenden, a computer science student, with whom he rapidly falls in love.
Tom and Luke's activities in Trabizona, Italy also figure in the story, with episodes involving Tom's gay boss, Professor Sescantanto, and Luke's struggles in his job as assistant opera house manager. The noble family background of Dominic, thought by the boys to be an inseparable barrier to him forming a permanent partnership with Sandro, turns out unexpectedly favourably when Dom's grandfather, head of the family, admits to being a closet gay.
Sex with Dom proves to be good for Sandro's academic performance. He gets a first and a prestigious research studentship to study for a PhD.