Her difficulties, and that kid right now is the time for her age, a teenager. Usually a teenager has these kinds of thoughts and sees their insecurities and often think those kind of stuff.
Jenny's attitude is normal for a average teenager. As a teenager, you feel moody and want to get mad at someone for no reason. And the reason Jenny thinks life is hard is because she's a teen, all teens feel that life is hard sometimes, so that's perfectly normal.
