It's interesting that you refer to the romances in wuxia novels as perfect. I seldom think of any of them as perfect romances. Most of the people involved in those relationships are very flawed people. Their relationships frequently end in the deaths of one or both characters, or are interrupted by terrible events that threaten to keep them apart forever. That's not perfect romance in my book (not that any such thing as a perfect romance actually exists).
I agree, at least with your statement about SPW. I guess that's why it's my favorite JY novel. And as you say, there aren't any really unrealistic romances in wuxia fiction; as strange as some of those relationships are, such things do happen in real life, too. Well, except for getting poisoned six times and surviving, or living comfortably at the bottom of a chasm for 16 years, or things like that.