I agree also on the fact that it's a figure of speech. I don't think he's really going to put sexual scenes, or drug-related scenes because... well... there weren't any in the book. But I think he meant that he was going to get deeper into their character because they're getting older, and deeper into the romances because they're clearer in this book than the other books.

But really, you guys shouldn't worry. David Yates is a wonderful director. I can't wait or HBP.