Yeah, Kariu is an annoying character, but that's because she's very human. She's prideful out of insecurity, and a jerk out of frustration. She really should apologise and make up with Tamarai, and at some level she probably knows that, but when you are in the middle of an emotional turmoil, it's hard to see beyond your own problems, and it's easier to hate someone else than to accept your own powerlessness.