answered:
it’s a trope in tv and real life to get a bob sort of haircut when a (normally female) character is bi or presumed to be in a relationship with a girl!
some examples:
also in the bi community when you have a haircut/ get a haircut like this you call it the “bi haircut” i have a ton of friends who came out as bi/pan who had/have this haircut. it’s basically just a funny coincidence that turned into a trope!