Your canon material for study: 'That Naughty Flashback Scene'
Ready, steady, GO!
What stalkingheron said.
But I must add that I think there was a definite element of "villain love" going on with K & L, while B's love for her is a slightly different kind of animal. (What we might call "hero love". Chaste, pure, wild intimacy held off until after marriage, endless obstacles, that sort of thing. While K&L's would say, "Hey, there's an unused pressure chamber over here! Let's test it!")