Yu choose to save both humanity and Mika which is different from other so they have to separate. Shinoa has a crush on Yu and She's using Yu as a desire and desire is power in this manga. Guren and His girlfriend are... idk I feel like there's more than "want their family back" I feel like that's their goal but theres more than that
Yu and Mika have had their own goals since meeting again, Yu has always made it clear that he wants to have Mika by his side. The fact that they separated was due to Yu's perception that everyone there was making choices and he was making the sacrifices, they both want to have their own way out of all the chaos they were involved in.
Shinoa has already made it more than clear that her ultimate goal is Yu, even if it is necessary to kill Mika for her to get what she wants, she will do it, it is not just for a source of power.
and Guren... until now he shows that he wants to undo the mistakes he made and led to part of what is happening. Even if to do so he is making even more mistakes.
75% of the chapter was just unnecessary love talk.
It always seems like the author wants Shinoa to be Yu's ultimate goal romantically, to the point where the character's construction makes her completely irritating, really, is romance the only goal in the midst of so much going on?
not to mention the point that there is no person who is not selfish. like, yu did everything to please everyone and the only thing he wanted was mika. and everyone wants him to be the one to sacrifice everything, shinoa wants yu for herself, guren and his girlfriend want the best for themselves, everyone wants their family back and all at the expense of yu's sacrifices