It's an offense, but it seems that due to her inability to read the mood, she could've missed obvious hints by the plotting guy. I really hope nothing bad happened to her.
Before cosplaying the char, you gotta ask if he's the kind who uses meta characters (since he mentioned that the new char is strong), or is he liking the char for waifu-ness, or both. If it's only for meta, then cosplaying it may lack... certain charm.
But all in all, if you're the apple of...