I think thats actully the point. Both mafuyu and akihiko were in love with people and a part of them will always be with those people. But slowly their moving on to people that make then feel loved and take all their bad parts along with them. While mafuyu doesnt hurt uenoya as much as akihiko does haruki but mafuyu always shows this lonly face that uenoya noticed and is hurt by it. But he understands that mafuyu is going thru alot doesnt mean its right but he puts up with it cuz he loves him.
Same with haruki. Haruki knows akihiko was in love with this guy for a long time and its difficult to stop loving someone haruki even tried it. So he wasnt so much as hurt by akihiko as much as his own feeling but later when akihiko started understanding his own feeling he realized who he loved but needed to end things right with the other guy so he wont have to hurt haruki.
We see esrly on too the akihiko dorsnt really want to show his bad side to haruki this being before he really fully understood his own feelings towrds haruki.
So i dont think the author wanted a stong apology because i feel like there trying to say apologies wont come. You shouldnt be sorry over how you felt towords someone instead you should try for your new love and be the best you can be there. Not perfect.
Rereading the akiharu parts and i found myself pissed for how it turned out.....we've got a lot of chapters on Akihiko trying to realize if he wants to break up with Ugetsu and then half chapter for us to see that he changed and wants Haruki....he was really selfish with Haruki, he hurt and used him, he didn't show love or care and i really wanted to see more effort and love-showing from him before getting together with Haruki, i wanted to see a more hearted apology....i feel the relationship is unbalanced and i can't see Akihiko trully in love with Haruki