“I will be the best for you”
“I will never disappoint”
“I will fulfill all your dreams”
“I will stand upto your expectations”
“I will always, always be there”
“I will do everything it takes, for you”
All she wanted was an affirmation. Hearing those, she believed in him.
Only later she realized, not all promises are kept. A word uttered is not always a word meant.