Since the manga isn't over, nothing's set in stone, yet. So, I can only give you my assumptions.
I'm actually quite sure that there is or will never be a romantic vibe between Tatara and Shizuku. As Prasanth has already said, Tatara probably never held any romantic feelings for her, but rather admiration and respect.
Moreover, the main heroine actually is ...
I was searching for this for a while, looked through the OST, Disc 1,2: Youtube The soundtrack was released on the sixth of December 2017.
BallroomEYoukoso subreddit user "BeKley", said:
"It’s part of the Ballroom e Youkoso OST which hasn’t been released yet unfortunately.
However, someone has made really accurate covers of these OSTs and they’ve also ...
I don't know the answer to your question but you can't find it because Yuuki Ayashi, the composer of the background music, hasn't released an OST yet.
I was searching for background music too... ^^ Not that particular one, but several pieces of music in the score of this anime.
Guess we have to wait a little more before finding it.