noun
frenemy; frienemy
A blend of 'friend' and 'enemy'; refers to a person who acts like a friend but is actually a rival or has hostile intentions. Used in casual, often social-media contexts.
彼女は私のフレネミーで、表では仲良くしているけど裏では悪口を言っている。
She is my frenemy; she acts friendly to my face but talks behind my back.