Bear in mind - the intention of Friends is to negatively affect the disposition off the charmed person once they realised you used magic on them. 'Hostile' in D&D is a dispositional state, meaning that they will generally not want anything to do with you, will not be inclined to listen to or believe you, may threaten or warn you away, and will generally be hostile; it doesn't mean "They will attack you".

Translating into a video game, where 'hostile' has a more tangible and hard-line definition, this is often misconstrued to the point were a creature charmed by such a spell will go 'red border' and literally turn combat-hostile at you once it ends, and that should not be the case unless they were already inclined to throw down with you. If this is happening here, I'd encourage people to submit it as a bug report to Larian's formal bug form (Here), and give the feedback that it shouldn't do this.