I still have trouble believing Arisa was the aggressive one...
Old Arisa was good about keeping a satisfactory consistency of shenanigans. Because this amnesiac one is still a little clueless, the normal frequency was lost and Mari may have been left too thirsty to remain passive/submissive.
On a more solemn note, Mari may also have some sort of deeper fear about their relationship because of the matter of amnesia... or rather, because of the notion that the amnesia could become worse. She may simply be projecting this concern about Arisa by coming closer to her this way.
... or, having looked ahead, even more worrywartish... Mari is plain-ass afraid of losing Arisa TO ANYTHING.
Go to sleep properly and get well soon...Arisa:
She lost her memories with Mari due to amnesia.
Very optimistic.Mari-san!But I'm not that badly sick!
I wanna watch something!Eh?...Okay?Mari:
Arisa's lover.
She was the submissive one in their relationship prior to Arisa's memory loss.Won't let you not sleepI'll stay here and make sure you're sleeping properly.So sleep.Okay!She's so aggressive today for some reason ♥♥