Fellow bi woman here and I totally relate to all what you said about Aerona. Honestly, i even felt a bit of anger and guilt towards the 5 year forgotten Seren and her toxic attitude towards her.
She deserves way better than that manipulation. I like immediately fell in love with her personality. When you get to know the soft emotional, lovable interior under the hard exterior it's just magical.
I'd highly reccomend buying the NSFW version if you haven't. It deepens the romance, emotions and has no off-putting male gaze.
I also chose to romance Yì Kâi and was also falling for him. The final choice between choosing between him and Aerona was really really difficult.
Although I know the jealousy Aerona felt...I just wanted to see him smile. I relate with him on the body image issues and using something that would harm you over time to look better. He's such a pure soul that you just want to hold and protect. I also absolutely hate how forgotten 5 year Seren treated him, she doesn't deserve him at all.
So i was torn between choosing someone I want to protect or someone I want to be protected by. I wish there was an ending where you could leave Yì Kai home, travel with Aerona, and come back to the island, then again Aerona has gone through a lot of stress because of Seren, she's within her full rights to refuse.
So you're right, it left me a bit broken either way, especially since i don't know how Yi Kai ended up after I left him on the ship.