Amity never had any social life after what happened with Willow, she couldn't stand Boscha and her gang and didn't have any actual friends; she only hung out with them superficially (it means fakely) under Odalia's influence. Once Luz befriended her, Amity's life got a million times better and she was actually happy for the first time in literal years.
Same as the one with Luz, Amity didn't wanted Boscha and her gang to find out about her true friendship with Willow, so she tried to burn the photo memory of their childhood friendship.
Boscha was not fully aware of Amity's blackmailing by Odalia until presumably during the timeskip in the finale, in which they probably became friends for actual this time.