At first, Robert returned to the living room because he wanted to ask what Ian wanted to drink; he didn't expect to stumble upon a discourse about their relationship, and he found himself standing still behind the partition, listening to the conversation even though he probably shouldn't.
But was that not human nature to be curious?
He knew very well that Eugene was critical about his relationship with Ian. While the omega never told his dad to stop seeing Robert, he didn't exactly welcome the bodyguard warmly.
Robert understood, though. It hadn't been long since Eugene mended his relationship with Ian, so he probably wanted Ian for himself for a bit longer. There was also some degree of distrust because Ian had just come out of a miserable 'relationship', and it was normal for a son to feel worried that his dad would get hurt again.
