I do feel bad for Ema, but she's really putting Takara into an awful situation here. At this point she has all but said "I want to leave this life behind and elope with you," but they both know that's something Ema has to do on her own and she just does not have the confidence to be true to herself, or true to Takara even. And maybe the only reason Ema hasn't taken a step forward yet is because she's afraid that Takara will just abandon her again the moment things get too real for her, just like when they were kids.
But, how is Takara supposed to prove that to her without becoming a homewrecker? Like sure, she could've let Ema kiss her and officially confirm it's mutual, but that doesn't necessarily mean that would give Ema the courage to leave Hario. They could be stuck having an affair for who knows how long and I doubt Takara could handle the guilt or keep up the charade of just being best friends, girl is awful at hiding her feelings.