I can honestly see them pulling the trigger on it at the end of this season. This season's pretty emphatically pushing the gang past their former status quo-- Mariner has supportive superiors, now what? Boimler is in charge sometimes, now what? Figuring this romance situation out would just be running with the theme of growth and change.

I'm happy either way they end up, although I think Rutherford's comment about green eyes is telegraphing there's something there, even if he and Tendi are oblivious to it.