In The Virgin Suicides, Cecilia Lisbon, the youngest of five sisters, tries to kill herself. It is evident in the previous scenes that she is unhappy, and after her attempted suicide, her parents get her help from a therapist. Eventually, Cecilia jumps out of her window, falling to her death. The remainder of the movie shows the other four girls trying to cope with her death, as well as live their lives under their parents strict rules. The Lisbon parents make their rules even stricter when one of the girls, Lux, stays out all night with a boy. They are then unable to leave their house, even for school, and kept in complete isolation from the rest of the world. This then drives the four girls, Lux, Bonnie, Mary, and Therese, to make a suicide pact, and they all kill themselves on the same night.
In the video above, a therapist is talking to Cecilia, and he says, "...you're not even old enough to know how bad life gets." She suggests that she knows how bad life gets, just from being a teenaged girl. Cecilia is so depressed going through adolescence, that taking her life seems like the only answer.
Also, later in the movie, when Lux appears to be rebelling against her parents' strict rules, her actions could be confused with depression. Parents often mistake depression for rebellion, and Lux could have been feeling depressed from her sisters death, or her lack or a social life. When the girls made the suicide pact, it showed how much their parents restrictions had completely ruined their lives and caused them to be depressed.
