シスターコンプレックス

noun

sister complex; excessive attachment to one's sister

Refers to an unusually strong emotional dependence on or obsession with one's sister, often used in psychological or colloquial contexts. Similar in construction to 'mother complex' (マザーコンプレックス).

• 彼かれはシスターコンプレックスで、妹いもうとの結けっ婚こんを素す直なおに喜よろこべなかった。

  He has a sister complex and couldn't wholeheartedly celebrate his younger sister's marriage.

• シスターコンプレックスが強つよいと、姉あねに彼かれ氏しができると嫉しっ妬としてしまうこともある。

  When someone has a strong sister complex, they may feel jealous if their older sister gets a boyfriend.