"Gay appeal" is probably the right word but I think the ambiguity also remained due to the lack of evidence about Ulliel's background. Although, I think the relationship between him and Béart was grounded and had more to do with the rising sexual tension and the lack of any other male figure around her.

The key scene obviously is when the two finally do come together and how the dynamics play out. When they're about to have intercourse, after some animalistic groping, Ulliel prefers anal sex as that was all he had experienced in reform schools. Also we hear him say that he has never been around too many girls. It was never in question that he wasn't straight...at most he was a bisexual.

Téchiné talked about this scene in an interview which is on the DVD, and it was surprising to hear him say that he contemplated taking the sex scene out but at the end went with it as he had written it in the original script. Gilles Perrault, whose novel the film is based on, said that in the novel the two men who arrive at the house do attempt to rape the female character but the boy saves her and only then she gives into him. I think Téchiné made the right decision otherwise on screen it might've looked a bit too dramatic. In the film he has one of the men showing his family pictures to Béart and that's when she starts to reminisce about the past and finds the youngster waiting.