At that point in time, there was no need to keep hiding things from Alissa since she could read minds, and she definitely will ready Ryan's mind once they see each other again.
"Alissa… the situation where you and Orgar became partners was rather… problematic," Ryan said after a long sigh. "I don't know the details, but it looks like he gave you his power without offering a pact. That had some consequences. The most drastic one was that Orgar's spirit would be fused with yours and then his individuality will disappear."
"What? How do you know that?" Alissa asked. "Why didn't you tell me this before?"
"It was Orgar's decision, he told me about it and said that I should keep it as a secret," Ryan replied.
"… That is not possible, I don't feel any different than before," Alissa said.