It was a very passionate car sex scene, which took many hours to film because of all the technicalities involved. The positioning of our bodies and the filming of it from many different angles took many takes to get right.
If you do the sex scene, it will hurt me, said his girlfriend.
Local actor Shane Pow chose to do the scene anyway because it was his job.
The fact that he chose his job over her caused a serious dent in their relationship, and was one of the things that led to the eventual break-up of their five-year relationship earlier this year.
Pow, 24, told The New Paper: "When I told her about the scene, she got angry. She asked me to put myself in her place, and asked how I would feel if I were her.
"But I told her, work is work.
"I was still going to do it. Nothing can be changed."
The English-language movie, tentatively titled Ms J Contemplates Her Choice, is a Jason Lai-directed thriller starring local singer Kit Chan and Italian-American DJ Bobby Tonelli.
In a flashback sequence set in the back of a car, Pow plays the man who romances Chan's character's younger self (played by local actress Seraph Sun).
He said: "It was a very passionate car sex scene, which took many hours to film because of all the technicalities involved.
"The positioning of our bodies and the filming of it from many different angles took many takes to get right.
"So even though we were both lying there half-naked for a long time, it really was just work."
Pow also found it to be a rather awkward experience as he did not know Sun.
After their two characters get into the car, they start making out and shedding their clothes. While Pow is topless, Sun still has her bra on.
He said: "There was a lot of kissing and caressing.
"It was awkward when she was on top of me and there were a lot of people around and we were just waiting for the lighting (to be done).
"We just lay there in silence. I couldn't exactly say, 'Hey, how's your day?'"
While his choice to film the scene did take a toll on the relationship, there were other reasons as to why their relationship went belly up, he said.