So I know it's generally said not to judge a book by it's cover (or manga in this case). But everytime I've seen a GL's manga with 3 people on the cover, the person behind the main character never ends up with them. It's always the person the main character is facing. Also saw someone said people don't know the difference between love triangles and love interests. So I think the love interest comment makes the most sense in terms of this trend I've been seeing. In the beginning though I always thought it was love triangle because how some stories start off and I always wondered who they would end up with, but sure enough by the end, it always ended up where the person in the back was never anything serious. Either simply a good friend who had a crush, or just a love interest that didn't build much of a spark as opposed to the person they are staring at. Maybe it's all just nonsense on my part lol but sorry for the long response.