The question surprises Flayn, mostly because she never considered it before. It takes her a minute to realize it's in the context of maybe wanting a date with Yukimura, and...

"I'm not sure I know," she admitted, after a longer think than usual. "I... hmm..."

She glanced at the door, knowing nobody was going to overhear them, but...

"I did not know either well at that point, but I cannot say I like Marui-san more than Yukimura-san, or vice-versa..."