Mmm not exactly. After reading that vol 5.5 chapter, it basically says that Yuuta has a small crush/attraction to Mahiru, not a full blown or passionate hidden love or full on feelings for her. If he really had a crush, he'd be showing more emotion or feelings on his face, but he doesn't, which means that he doesn't hold strong feelings toward her. At most a slight sting or disappointment or regret, but he ain't dying from heartbreak.
He thinks that he and Mahiru are cut from the same cloth (both being super popular and attractive yet only showing their personas to other people) and develops a slight attraction toward her, but realizes that the small feelings he has for her are just toward her "Angel" persona and not actually Mahiru herself (kinda ironic since this is the exact thing he dislikes and is happening to him with all the girls around him; basically explains why he doesn't date anyone cause the girls see him as a kind of object/trophy and not see him for the guy himself). So when Yuuta sees them on their date, and Mahiru is happily in love "like an ordinary girl", he wants to root for them and their happiness. And he knows that Amane is a good guy, so he has no hard feelings for him and really wishes for them to be happy.
