The only reason Umika wanted to leave Earth it's because she thought there was nothing on Earth for her, with her learning to talk normally and interact with people it's obvious she'll decide to stay after all, which means Akeuchi will have to make the decision at the end there, it's on her. But for that ending decision to be truly impactful they need to get together first and already had been together for a while, so I'm sure it's gonna remove the subtext tag soon (as soon as Akeuchi stops overheating). The question right now it's what's gonna happen first, a confession or Umika realizing she is gay too?