While Noelle is my favorite character I'm not sure she has a romantic as much as sibling relationship as it relates to ASta. That said she has been abusive to him physically, verbally, magically, so I don't think that can be tolerated in a real relationship outside of siblings where that stuff is common. She might make a nice mother though the man for Noelle is Zora. He put her entire family in their place while saving their lives... So its not like NEbra or Solid can say anything because he will put them in place verbally without violence unlike Asta who needs to resort to that or yelling with his limited mentality
. You can see Noelle was told by her brother Nozel that men are talking when she tried to chime in when Zora challenged Nozel as a failure to be the man of his family by not protecting his siblings etc. She instantly knew her place without throwing a hissy fit or anything... Even if she tried her shit with Zorta his trap magic would turn it back on her. She will become a better person as well as mother when she marries Zora eventually. He will really put the royals on their asses while getting revenge for his Father Zara. He was a good man/father not just a dad so I think that will help them raise a proper family instead of trash or have a toxic environment like Noelle. She never knew what it was like to be decent or act in a manor of a human to display love for another so needs Zora to keep her in line.
Mimosa besides her issues with brother is the perfect mother type. She has a really big chest so it makes her look chunky but I think she is at least as pretty as Noelle or can become hotter if needed. She worked hard to become stronger so she could fight alongside Asta, she was on his back healing him, she never disrespects him or acts like a fool like Noelle. IF Asta was her man she would lose weight working out with him just be be around him more or if he told her to get in shape. I think Asta gets along well with all her Vermillion relatives so that would make it a much easier environment to raise children properly in. I don't think Asta will end up with either of them though. She does have those child bearing hips for somebody like Asta who would want to have like 10-20
. I personally would rather marry into her side over the Silva side if I had the choice. At some point chicks like Noelle get old, unless she gets a better attitude to match that Valkyrie dress
. Besides I could even see her end up marrying Yuno to unite the Heart/Spade kingdoms or foster peace in some manner like a royal should
.