@Harusame Jiu is right though. This is fucked up. Now what, Mao is going to have to walk on egg shells because the lake god is literally jealous Mao's becoming acquainted with men? Really? Mao is a really passive person and hasn't been shown to really think about what they truly want with the situation, but certainly I can't imagine they're fine with the status quo, being the bride of a jealous lake god who will seemingly magically summon him back to the lake whenever he gets too jealous.
Jiu isn't jealous in the way that he's in love with Mao and wants Mao all to himself. He doesn't want his friend being pulled along with this ridiculous charade.