Preoccupied Attachment: (Also known as anxious-ambivalent) Relationships that are characterized by feelings of unworthiness, apprehension, jealousy, uncertainty, or possessiveness.
Glee Season 3 Episode 18: http://www.tvshow7.eu/glee-season-3-episode-18-choke/ (See Alternative18:00-19:05)
In this clip, Coach Beiste is showing preoccupied attachment. She is married to an abusive man, but does not leave him. As shown in the last 10-15 seconds of the clip, her reasoning for staying with this man is that she feels as if no one else will ever love her. She feels very unworthy (she believes she is not good enough for others to like her) and apprehensive (she worries about being alone for the rest of her life). Therefore, she stays in the relationship she is currently in.