[It feels like an insult after "I love you" and she hates that because she feels closer and more intensely about him right now than she realized she felt. Almost losing him or the fear of almost losing him made her realize how much he means to her but she was telling Reid those same words not so long ago. She was still easing into things. She's not sure how she feels right now. It hasn't had time to sort itself out and be clear to her and doesn't want to say something like that unless she feels it with absolute certainty. He means too much to her for that.
She bites back the urge to say he's been through a lot and he needs time to sort it out too. She doesn't want to doubt his sincerity. She doesn't want to reject in any way even if she can't fully reciprocate.]