Well, on my 3rd playthrough, it finally occurred to me why exactly Jessica is treated as the official love interest for the story even though she's (imo) the least interesting: It's to keep her relevant.
Every other woman in the story has their own storyline/character arc. Besides the obvious like Madalyn claiming power or Sofia breaking her curse or Clare finding lost treasure, there's smaller scale ones like Alia finally gaining some independence, Emily proving herself a successful businesswoman to her father, or just Kaley overcoming her fear of intimacy. Jessica? She's got none of that. She heals you, fucks you, and helps Emily with her experiments. But if she wasn't the love interest, she'd have nothing of her own.