This is just another cultural difference. I know it doesn’t make much sense to us Westerners, but for the Japanese, you’ve gotta clearly define what kind of relationship you have with people. Not sure how long you’ve been reading manga, but this whole thing about defining relationships is super common. It’s not unusual in manga to see characters who’ve known each other for a while freaking out when they find out one of them already thinks of the other as a friend.
More precisely in her case, her "previous (?)" thinking patterns sound like :
1) Not to contradict her father's creed : "Never show any weakness (TO ANYONE IN THE MULTIVERSE !!!)"
2) If a worthy boy aims to become her lover, "HE MUST START AS A FRIEND FIRST" to build leisurely and safely a betrayal-free trust.
3) "Wouldn't trusting enough any stranger enough into becoming my friend LEAVE ME OPEN TO BETRAYAL ???!"
4) As she ended friendless (and severely clueless about relationships) under these rules/conditions, she needed additional rules/criterions/advices to select and invite a lover candidate "assessed worthy" into "MANDATORY FRIEND zone" trial.
At she already talked Minori about the point 2), she MUST apply her own "convictions" by not skipping the "FRIEND zone" step : roll credits ! (What was this manga's title again ?)
P.S. : Minori, if it will get too tough for you, leave the rest to me : I _ C A N _ F I X _ H E R _ !!!