Hermione was trying to focus on her breathing as they parted from the kiss, so it took her a moment to realise what Ernie had said. He loved her? Well, the swoop of happiness in her stomach was certainly just as surprising, and she was surprised to find that she wasn't completely freaking out.
"I think," she started as diplomatically as possible, her fingers still stroking through Ernie's hair. "I think we could have something very good, Ernie. I think- I really think we could-" Hermione really didn't want Ernie to think he was being rejected just because she wasn't saying the words back right now. She was rapidly falling for him and she wasn't afraid to admit that.