"... that what we feel for each other is more than just friendship," he finished for her, slowly. "We're dating now, but we haven't told anyone else. Mostly because we wanted to tell you both first."
Ginny's mouth was in a tight, thin line, and she was now giving Hermione a scathing look. After all the things she had shared with Hermione -- all her confessionals about her feelings for Harry -- and now this? And him! How could he do this? Well, it wasn't as though she had ever expressed herself to him, but still. She wouldn't be able to forgive Hermione so easily.
Taking in Ron's and Ginny's expressions, particularly the mean look Ginny was giving Hermione, Harry immediately took the defensive. "Look, it wasn't exactly her idea. It's... well, both of us."
He gave a small sigh and looked at Hermione helplessly. So, he had been wrong about them taking this well.