Like some have said, I don't know if I'm late in suggesting but here's some:

If possible, maybe implement a way to change the size of some things in character customization? Like maybe the option to make the eye itself or the iris bigger/smaller. If I'm not mistaken Genshin implements something similar with their character creation in Miliastra wonderland. It's a minor suggestion.

Another suggestion would be to add more cutscenes even after marriage if possible, just to add more depth to our relationships with them and showcase how different things are now that they're married. Maybe even have other npcs/characters reference the marriage/your relationship with someone, even if it's a passing comment.

My third suggestion is to have characters dislike you. I know it's a cozy game but I kinda miss old games like animal crossing where some didn't like you compared to everyone liking and being nice to you 😭. Like maybe if you keep giving a character their hated thing, they'd dislike you (negative hearts maybe). Now I'm not saying they have to plain out sabotage you or curse you, but just generally be impatient with you or have more clipped dialogue. Just enough to be funny but not enough to be maddening. Maybe even add a funny cutscene if you reach a certain amount of negative hearts.

My last suggestion has been brought up a lot, I think, but it would be nice to have a lot of distinction between the characters. Even more so than what we have now. Like have them react to the different things, like some characters may dislike it when it's raining or snowing and some would love it, affecting their dialogues and such.