It's interesting that while Hiiragi idealises and still holds "Yuki-Mafuyu" as a perfect first love- that moment he made the freudian slip almost calling it Ue's song, maybe he has started to give Ue some credit
And really, first love is beautiful and Yuki was amazing, the truth is that Mafuyu is in love with Ue now. Regardless of what people suggest him to do, it is upto him. It is almost imposcible to just "get over" Yuki's loss, and Mafuyu is trying his best. As long as he and Ue communicate well, they should be ok.