I think it will be a terrible series. After 2 or 3 episodes, they will act as if he is not gay and has never been…
I think you haven't read the synopsis properly yet. The ML's brother is gay. Due to pressure from his family, the brother hires FL to act as his wife. The ML doesn't want that to happen because he wants his brother to become the CEO, which will not be possible if he marries her. The romance is between ML and FL.
2- Yes, they are solving new cases per 1.5 ep. Along with that, the past of the characters is getting explored.