If "fine" means for you pseudo perfect girl beng stressed that her lover is much more beautiful with much lower effort then you're sick af.
I think the only one getting stressed out here is you. Take a few deep breaths and try to be a little more objective. You seem to have a personal issue that you are projecting on this story.
Very clearly this story is not about perfectionism or an unhealthy relationship. Fujishiro's reactions are comical, not serious stress and Kurokawa has an inferiority complex, which is way more harmful to her than anything Fujishiro does for her.
I think you completely overlooked how happy both of them were that Kurokawa was so cute. Fujishiro wouldn't be angry that she puts so little effort in her looks if she didn't subconsciously like Kurokawa's cuteness (even if she is the competitive type).
Kurokawa secretly wants to stand out sometimes and be the "princess" in the play as well. She doesn't have the confidence, but that is what Fujishiro is giving her. Her life until now was filled with escapism and fake peace, but now she was drawn into a whirlwind of new experiences and emotions. You might call that "stressful", but it's nothing bad. This can only help her grow as a person. If she truly didn't want to be dressed up and called cute by Fujishiro, hell, she could have fooled me with all that blushing and smiling!
Good relationships can also be ones where the partners challenge each other to be better or leave their old habits/comfort zone to find new things that might be much greater.