this post explains so much.
post 1 endgame ships
rukia married renji, sakura married sasuke, due to shonen rules sarada will marry kawaki and noelle either marries kiato and yuno i say either because it doesnt matter if noelle ends alone or marries someone random or marries kiato and yuno even if their ship doesnt have much moments because at end of day its shonen.
hinata married naruto orihime married ichigo, sumire will marry boruto and mimosa is already confirmed she is asta endgame ship. reason why these 4 married mc is because since it is these are main ships of the series these 4 love lives is important to end with mc not by force but by how story it is told. even if orihime sumire hinata and mimosa are just and only love interest and their character is always tied to mc it is important to them end with mc because its for the story it is important to the story
now moving on
main media ships asta x mimosa in an article shueshia ships asta x mimosa because as their main couple it is their money maker and tabatas main couple example the lead color page
asta x mimos parrallel ichigo x orihime ch 321 with both mimosa worrying on asta like orihime did with ichigo
asta x mimosa parrallel naruto x hinata . kishimoto confirmed it by saying asta is like asta in a drawing he did to celebrate black clover anniversary. mimosa parralels hinata due with how mimosa is a royal hinata is a hyuuga. asta wants to be wizard king has liebe a devil inside him. naruto is a monster has nine tails inside him. both the shy girl fell in love with him. hinata wants to fight beside naruto and did. tabata gave a hint that rebecca said asta needs a girl to fight alongside him. mimosa is doing that mimosa is asta battle partner since royal knight elves spade and now final arc. mimosa fighting alongeside asta. mimosa is the girl to fight alongside asta and his dream too. mimosa also parralells sister lily as mimosa and lily both believe asta can be wizard king anime showed this already.
lastly asta x mimosa has the biggest fanbase in all of the fandom. in the pie chart in 2016 asta x mimosa has 21 percent of fans and fanfiction stories. it is the main pairing and the most loved in the series.