Girls, would you be okay with your boyfriend going to a concert alone with your female best friend?

So, there's my boyfriend (who's the best companion I could wish for, been together for two years) and then there's one of my best friends (let's call her Sarah). We occasionally hang out with other people. Now, Sarah is an exuberant girl, who was always caring and considerate towards me. She always takes care of her appearance, is pretty bright, and has some masculine hobbies as well as a large group of male friends. I don't think she would ever cheat on me, but she's been insecure about her looks in the past and this made her obsessed with the idea of boys being attracted to her (pretty sure she overcame that phase). We were in a library yesterday with another friend (we form a best friends trio that sometimes includes my boyfriend, as they appreciate his company), and Sarah casually asked my boyfriend -who's a musician- to go to a popular concert with her, since she was looking for someone to go with. Girls, what are you doing in this situation?
Girls, would you be okay with your boyfriend going to a concert alone with your female best friend?
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