The [L/N], much like the Malfoy's, is a very prided pure-blood family and a very power lusted one, at that. This family had always been close with the Malfoy's mostly because both lineage are closely similar to one another, and both lineage are acknowledged by the dark lord himself.
Of course, as expected, both families' progeny has a wonderful relationship budding between them, although this is what you'd call friendship. [Y/n] and Draco have both known each other since they could say 'mama' and 'papa' correctly, and they have been best friends and inseparable. Naturally it was expected for the two to have a better and deeper relationship than what muggles call 'bestfriends zone' but there were things that needed more push than it usually should.
Certainly, a big issue between each other's perspective was also a big reason why the two were close but not quite to the point. One contradicted the other in many different ways. As everyone knows, Draco is just like his father, he sees nothing but blood status, he thinks of himself as the prince of the world (Of course not the king as it would be his father), he most despises muggles and muggle related things, and he can be a bit of a dramatic scum.
Now let's take a look at [Y/N]. Despite her blood heritage, she had always been the odd one out. Sure, she was a slytherin but other than that, what else could prove that she was the prided [L/N]'s brood? Unlike Draco, she may think highly of herself, but she doesn't go around yelling at people that her parents are going to go after them if they make a wrong move just because she thinks her parents matter a lot in the wizarding industry. She was the ideal heroine, a reserved yet... beneficial lady to be with. And to top it all with the Malfoy/[L/N] null shipping, she liked muggle candies, especially this sticked candy called 'lollipop', she loved it so much that she would eat it infront slytherins... and much worse, infront of the egoistic Malfoys.