Bill hadn't really meant to stand Jack up for their talk on the Time War. It was just conversations got out of hand and her emotions were getting tossed around like a tempest. It was driving her mad, the idea of not telling the Doctor everything. And then River flip-flopping on the spoilers. And knowing she would have to die. That was the hardest.
So when she heard Jack's voice outside of her door, she sat up on her bed and hoped he would go away... But he didn't. So, sniffling, she wiped her eyes and got up to open the door for him. "I'm sorry. Things got... right properly muddled after we made plans. Just... A lot of back and forth."