Jiang Yi was not gay and wasn't pretending to be different. It was because he didn't want to expose himself or attract Yi Chan's special attention.
Yi Chan probably didn't recognize him; otherwise, she wouldn't ask him such a question. Jiang Yi looked at her and didn't detect any special look in her eyes.
She should possess special abilities or divine skills, which was why she found Jiang Yi familiar. However, Jiang Yi's appearance and soul spirit aura completely changed because of Mirage Divine Ability. Thus, Yi Chan was just suspicious, but she didn't recognize him and wasn't certain.