As lame as Shiki's treatment is in the anime, I love how they paired them up for their debut solo songs on the Second Sparkle album. The bridges in both of their solos are the same melody and are meant to match the other, and they both use language that indicates they're singing to eachother. Mei's solo uses red as a metaphor and Shiki's has a line about her world being dyed red. Shiki's song uses glass being shattered as a metaphor and Mei's song has a line about fragments, it's not very subtle. Hell fragment visuals appear during Mei's bridge and the stage glows red during Shiki's live, as well.
I think the issue of pushing dynamics with a specific girl has been an issue in Love Live since the beginning. It feels like after the first season with them experimenting with the dynamics they're like "Oh people really like these two together, then let's make 90% of their interactions about them." And as someone who loves different dynamics and usually isn't attracted to the main ships a show tries to impose it's kinda frustrating.
