Neptune is just vain.
Also, Jaune *DID* finally back-off when he thought Weiss was happier without him, he just went into silent-berserker-mode when he found-out she was not in fact happy (and confronted Neptune for it). For a person who just recently discovered his spine about 9 chapters ago, this says ALOT about how much he cares about Weiss's well-being.
-I predict he will make efforts to avoid antagonizing Weiss in future chapters.
Afterwards, he wasn't after Weiss at all (that or I missed it because I'm still trying to block Jaune in a dress).
In short, Jaune is slowly pulling his head out from under his own ass.
