Finding romance a hassle is not the same as being aro, though. Them being alike like this, as Ruri puts it, is less a sign of this ship not sailing, and more one of them being highly compatible, as they can focus on their jobs as they want to, but also spend their free time together at home in bed without having to worry about the usual romance bits like dates. Old married couple trope style.
Not to mention like, one of the most popular yuri manga of the past couple years, had a legit ace lesbian ending (crescent moon and doughnuts). So it can be seen as either or.
Also if one actually read it, the note wasn't that she's ace. Just that she didn't have the time nor energy while idol girl is like 'yknow I could also go for something easy and lowkey'
It's a side couple flag lmao