

You are free to dislike people and to choose who will be your friends, your sister also have this freedom, maybe you could offer help if things get too rough with Lena, and give advice if needed, helping people is not easy specially if Lena doesn’t accept it or want it.
It is the Tendency to speak rapidly and frenziedly, as if motivated by an urgency not apparent to the listener if she is bipolar antidepressants could be too stimulating cause a person to feel the need to talk a lot and feel very uncomfortable when people are silent or between topics.