At first I thought that it was OK that things turned out like they did for the MC because Renka seemed genuinely oblivious to his feelings for her, but now she seems to have had her own strong feelings for at least some while. So now she's just perpetuating the misunderstanding, to her own obvious dissatisfaction, for no gain. I guess maybe she thinks she can't be in a relationship because she's an idol of sorts? If that was the case, she would have said something like that when he said she'd get a partner of her social status, but instead she just went "of course haha you're my childhood friend." She looks hurt when he brings it up and MC looks visibly miserable in a way that's really hard to interpret as anything other than him being torn apart by his yearning, so if she really does feel something for him and lets things keep going this way, it's really on her, isn't it?
If she turns out to have shot him down like 6 years ago because she wanted to focus on idol training or something, I will be extremely disappointed in her but not surprised.