@Shuzuchi
Because she has no title or any value except what she can do for the Oda. She lacks the status for the Oda family to bring her in like that, but Oda wouldn't trust any of his retainers to be her husband lest they use the opportunity to take her for themselves.
Letting her act...
@VoraciousEater
Hard agree, I liked the manga up until the end. It felt so forced and while I understand that the life and death situation provided the clarity to realize they loved each other, it felt like it invalidated all the relationship drama that's happened so far.