Okay, he may not have been nervous before but as Hermione stared at him, and the ring, dumbfounded after he'd asked, he was now terrified that she was going to say no. He couldn't even begin to work out the answer to her question. He just stared, the smile still on his face though it came closer and closer to fading.
Until finally she said "Yes." And then he kind of laughed nervously and asked "Are you sure about that?" But he didn't give her a chance to answer. He was lifting the ring from the box and then sliding it onto her finger. "Your mum was perfect on the ring size," he mused. "And um, two. About two months."
If possible he felt more nervous now than he had before. "You are really sure, right? Because I am. Completely sure."