The whole 'fantasy with realistic characters' debate makes me think about how we define 'realistic' in these contexts. Is it emotional reactions? Moral frameworks? Because honestly, a lot of the big-name romantasy books get praised for 'realistic heroines' who are just modern women plopped into a medieval setting with zero cultural adjustment, which breaks my immersion harder than any magic system could.
I keep returning to authors who treat the fantasy elements as a pressure cooker for character flaws. Like in 'A Court of Thorns and Roses', Feyre's trauma responses post-Under-Mountain felt brutally, uncomfortably genuine, even as she's dealing with faerie lords. The fantasy didn't erase the human cost; it amplified it. Same with Kathryn Ann Kingsley's villain romances—the love interests are ancient, powerful beings, but their obsessive, possessive behaviors are grounded in recognizable, if extreme, psychological patterns. The fantasy setting lets those patterns play out to their most dramatic conclusions without modern social constraints.
What ruins it for me is when the magic exists solely as a deus ex machina to solve relationship issues. Realistic characters, to me, are the ones whose personalities and wounds persist despite the magic around them. They use the magical systems according to their established traits, not just because the plot needs a spell cast. That's the balance that keeps me rereading.