About Dynazenon: Trigger series always go downhill when they focus on a traditional hetero romance because they're so busy with the romance that they forget to focus on the actual plot and world building.
My imagination is that Alice and Marisa are a couple, but since Marisa may not live nearly as long as Alice, she feels free to make the most of her years with Reimu, Patchouli, Sakuya, etc. etc.
^I was obviously talking about BP the poison dart frog you nit, not Glaucus the sea-slug (whose inspiration's physiological quirks and what implications they might have I have previously discussed at some length)