Seriously? That's a bit lame TBH
P5 improved a lot of things over P4, but something they didn't really address was how romancing a character affects events and dialogue outside of specific romance scenes.
On one end, I like that there's not too much emphasis put towards this, as a player could feel they were left out if they didn't romance anyone, and it'd probably become really complicated to design, depending on how many people you romance, dialogue choices, etc. But, on the other, it always feels like this secret relationship that can't be mentioned to anyone else, and doesn't make sense with certain story-important interactions.
It'd probably be really hard to improve upon this, but it's one aspect of the game which clearly has room for it.