I think setting up Fukami as a one-sided crush on Kase is fine, but the drama between Kase and Yamada could have been more clearly about prioritizing a roommate over her girlfriend since the series hasn't given an indication that Kase is wavering on the relationship. Instead the last panels of this chapter make it seem like we're going into the romantic rivals space - with this being about Yamada staking a claim to Kase. On top of that Yamada is apparently fine with the classmates not wanting Kase to leave, but asks specifically about Fukami in the last panels - it should have been definitely one or the other pressuring her to stay, not both.
If the author wanted to go the rivals route I think you need to make Kase more secretive about messaging specifically Fukami, and maybe have another situation or two where she prioritizes what Fukami wants to do over Yamada. Then at least Kase's role in the situation can be having potentially led the girl on by being flirtatious with her rather than just being spineless when told to race by a senior. It's interesting that it's not even specifically Fukami's challenge that Kase winds up accepting - she was turning that down until pressured by others. So you end up with a situation where I think the author wanted Kase to have to pick between Yamada and Fukami, but really got her picking between Yamada and the classmates? And ultimately this all boils down to Kase being spineless and not just committing to moving out.
I suspect the hickey title will be Yamada giving Kase one to "mark her territory," but the way it's been written that shouldn't have been the drama - the drama should have been squarely on Kase being at fault.