Oof. This is a hard test. But it will for sure show whether he can look at her instead of at her hair. (If it's a wig instead she's a superb makeup artist.)
@animekek69 Hair will grow out though, even if it'll be a year (or more likely two) before it's as long as before. (Female hair grows faster, asian hair grows faster, and if you have the ability to grow your hair long that's also because it grows faster than average).
@Fim There's this whole Japanese cultural thing about cutting your hair to show you are divesting yourself of your past life. So she's really saying "I'm grown up now". (Was originally some Samurai thing, but like you say it's mostly girls who get to do it these days, since boys don't have as long hair as they used to.)