The ending does feel tacked on, to the point that it doesn't even detract from wholesome part for me. I can just ignore it. There's an entirety of one little flower setting any of this up and I'm flower language illiterate so the implication doesn't really register even after having it explained.
And maybe it's because it's so tacked on, but it's hard to feel like this Marisa is that beyond saving, anyway. I mean, they have some time and Alice seems to have had a realization of her feelings so things could go a lot of ways from here.
All that said, Marisa being psycho about it is at least a fresh take on the tired MariAli lifespan drama so it's not like I hate it.