I don't know for sure. The ending of such a manga can be quite unpredictable and might not have been revealed yet. You could try discussing it with other fans to get their speculations.
I'm not really sure if they end up together. Different people might have different interpretations. Maybe you can dig deeper into the manga and form your own conclusion.
The plot might involve Sakura being held by Tomakazu in a way that restricts her freedom. She could be struggling because she has a different goal or belief. For example, if they are in a fictional world with different factions, and Tomakazu's grip represents his side's control, and Sakura is trying to get to her own side or do something that goes against what Tomakazu wants.
Obviously, Sakura and Tomakazu are the main characters. Sakura is the one who is struggling, so she's a central figure in the story. Tomakazu, on the other hand, is the one whose grip is causing the struggle.