I dont think that Mafuyu is selfish. I get that a lot of people are getting mad at him for 'using' Uenoyama as a way to grieve for his late love, but remember that Ritsuka knew of Mafuyu's past, he knew what happened, and he knows how much Mafuyu and Yuki loved each other. He was aware of all those things and is ready to help mafuyu to move on, or atleast find the happiness he deserves, he CHOSE to be with mafuyu, he put himself in that situation, and I know that he knows what might happen, and is ready for it, ready to support mafuyu no matter what happens. And if that's not love I dont know what is. And for Mafuyu, he opened up himself AGAIN to ritsuka, he was ready to move on but is still conflicted, because if you put yourself in his shoes you would also be confused. He loves Ritsuka but is asking himself 'am I really allowed to love again after losing the love of my life?'. Im still pretty much conflicted, but don't ever call Mafuyu selfish! He just lost his first love and bestfriend, but is now finding the strength and the person to love again. He's asking himself if he's moving on too fast, or what might others think if they saw him with another man after he lost his late lover.
I think it's not because Ue is aware of what it means to be with Mafuyu and that he is aware of his past that he must himself have forgotten his own feelings. He's a human being with emotions and limitations just like Mafuyu. Anyone would feel a little bad to see themselves compared to an ex who is dead. I also think that we should put ourselves in the place of the 2 and not just Mafuyu or Ue.
you also have to see it the other way around, getting together with someone who is going through a period of mourning is not easy for the one who is going through it and the one who is there to support it.(⌒▽⌒)
ANG CUTE NYO PUTSNGINA