We cannot change the past, and the future is often murky and unclear. But the present is ours to decide. That is why it is called the present.
Harry taking Diana, though she's a couple of years younger than him, seriously, treating her as an equal and simply being nice to her despite the fact he barely knows her. Sif points out how rare that is.
Several times, when Thor makes comments about Lily, whether he thinks them or says them aloud, he gets an breezy answer that is clearly Lily.