I have soooo many but I’ll keep it brief lol

-Haku definitely fell for Lee first, I like to think sparks started flying for her after he came in to save her (and Naruto) from Kimimaro
-Lee is noticeably a little calmer when he’s around her, like she has this soothing aura, which is part of the reason why Tenten and Neji like whenever Haku is around and accompanies them on missions
-Haku’s natural body temperate is a lot colder than most people, so in the summer when it’s hot and she sees that Lee is a bit flustered from the heat she’ll place her hands on his cheeks and it helps to cool him down a little
-their first official date is at that curry restaurant from that one filler episode with the curry of life
-they get married in the spring (springtime of youth)