The last time she said "I love you"
there was silence.

He said nothing.

And with the nothing he said, her world came tumbling down even further than it had already been.
He manipulated her,
He used her,
He disrespected her,
He belittled her.

He hurt her time and time again, but she was so in love with the idea of love that she kept coming back for more.
She didn't care that he didn't care about her.
She craved his touch, she craved his affection, and she would get it.
Only to be pushed away one final time, and realize love wasn't all it was made out to be.

The last time she said "I love you"
the silence broke her.

No wonder she's afraid of saying it to you.