I wonder how seriously they are taking it as 2 girls are engaged now apparently.
Yeah, that happened when I was in school - when I was like 9 there was a girl and boy who were 'engaged', arranged for us all to dress up for a party. I told my mother and she got me a black dress that at the time I thought was pretty, but in hindsight I think my anti-marriage mother might have been making a statement.
They're using language adults have taught them to use about their emotions and actions, which may not be the best but it's all they've got. I think there is a need for broader language around these things, to be able to discuss a desire for affection and recognition from another person without sexuality playing a part, but right now, that is not really in the cultural lexicon. Wider social systems have kinda reduced friendships down which is an issue, I think.
It's a complicated issue, but not one that's the kids fault or should just be dismissed as a fan when they are trying to communicate something within our limited social framework as it has developed.
My concern is that the popular girls will outgrow any label and be allowed to move on from it, the less popular may have a label used against them in future.
I can see what you're saying, which is why with my DD I discussed the importance of privacy, that once she says something it's out there and out of her control. I advised against coming out at school at her age when she has so little control of her environment. I'll support and love her whoever she fancies or loves, she can be 'proud' of who she is, she isn't less proud or less herself for not labelling herself at school no matter what her peers are doing.
No matter how many anti-discrimination assemblies the school has put on, she has had enough shite from people just assuming she's a lesbian because she's turned down guys asking her out as has happened since her first day at the school. She has enough from people telling her she isn't actually British because she has an immigrant parent. She has her little group of friends, but she's had a lot of social stress from being very visibly and audibly 'other' even in an objectively diverse school. Some children and adults are assholes.
No matter how accepted it can look within some circles, I would be doing her a disservice if I pretended and denied what she has already experienced just from others' assumptions of her sexuality that all of her peers will have a 'love is love' attitude to everyone who comes out. Most likely, yeah, the ones who are more popular will have an easier time if they later decide that wasn't the right label than others, but that's separate from the support a child asking 'would you mind' is likely asking for.