Because you didn't want to lose him, you lost yourself in the process.
You became a girl who kept being mistreated and you formed a habit of saying "I'm used to it".
You became a girl who kept being unappreciated and you began to tell yourself "It's okay".
You became a girl who kept being undervalued and you learned how to say "I'm fine".
You became a girl who kept being put last and you naturally reacted with "It's whatever".
You became a girl who kept being taken for granted and you dealt with it by repeating "Everything's okay".
You became a girl who kept being unhappy and you regularly told people "I'm gonna be fine"