Appreciate, Kiki's "dress" and "suit." Shion admires Kiki's comfort in her "dress," and desires to be part of that happiness. But, she realizes their relationship dynamic differs. It's not the attire but the partner that matters.
It's a Kiki and Michiru thing. Shio can't swoop in at the last moment, as with her, Kiki reverts to her old, uncomfortable "suit." Shio is not the right partner. She can only think the dress looks good, while Michiru says it.
Meanwhile, Kiki begins to understand her feelings. It seems she'll soon understand the phrase "absence makes the heart grow fonder," and hopefully not "ya snooze, ya lose." Also, big Sis is back!