Several people label these two octopuses a couple because they spend a lot of time together and get along well. I’ve been tempted to follow suit since I’ve seen wholesome snapshots of them talking.  I’ve also noticed a significant detail on Marina’s Doubutsu no Mori e+ e-Reader card that made me want to believe they are in love. The “Profile” section of the card reads, “... despite her appearance, she has a solid core. She's not moved by anything. Not even if that person is Okutarou (Japanese name for Octavian).” That implies that Marina and Octavian share a special bond unlike any other.  Unfortunately, I couldn’t find any evidence that these cephalopods are dating, but their friendship is precious regardless.