I do think a teacher should intervene and provide a much needed dose of reality, sanity, and a lesson on respect.
If it was the boys pestering the girls, I would hope someone would sit everyone down and explain how they were crossing lines that shouldn't be crossed. But it's no less serious when it's girls doing this.
"Hormones" whether testosterone, estrogen, or progesterone are not an excuse for pursuing girls or boys - but I see this as a case of mimicking material children have seen at home online, on TV, etc, or have seen older siblings focus on, and a problem in the class dynamics.
The tween years are a period when tribes emerge in school groups. The girls band together, and so do the boys. There can be sub tribes. Crossing the boy/ girl divide or being neurodivergent can be punished by the larger group.
There can be problems with bullying behaviour, particularly among girls - not knocking each other over and stealing lunch money, but subtle knowing looks passed between them, little sniggers when the target girl speaks, isolating a girl perceived as smelly or babyish or a bit weird (i.e. having interests the main group doesn't share, and not realizing she needs to hide her individuality).
If this dynamic exists in a class, it can make everyone watch their back and feel pressure to join the behaviour. It certainly is a teacher's job to keep track of the undercurrents in the group.
If one or two girls who are seen as leaders - in fashion or perceived sophistication or good looks - decide that declaring themselves in love is their new thing, or teasing boys gives them a sense of their own importance, it can catch on fast.