Subservient
Abject
noun, な adjective
A lowly person who yields to everyone is really subservient. They'll do everything people tell them because they don't have the nerves to speak up and just say no.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
どうしてすぐに卑屈になるの？
Why do you immediately become subservient?