There are a lot of sugestions people can give you, but I think one that nobody ever mentions is to make relationships less shallow.
Relationships in HM\RF advance primarly with gifts you force-feed unto people every single day (and you don't give more than one because it doesn't do anything, if it did you'd marry girls day fucking uno)
This makes some sense since the gameplay is about producing items and using them later for profit, food, equipment or gifts, but it makes for a very linear and samey gameplay, especially since once you figure a girl's gift, you literally farm her affection.
Case in point, RF3 has Raven liking crystals, so you can get quite a lot of them going around the forest and in a single day you have enough gifts for a week or more. (Plus Gaius is happy with Scrap you'll get as well) so her love for you becomes a matter of time.
Instead, what you could do is give the player a lot of different things and variables you can work towards and make those affect how people perceive you, different people putting different weights on what you do and thus you'd need to do different things to earn their friendship\affection.
For instance, the girl that sells flowers\vegetables\seeds likes plants very much. The more "green" your farm is, the more friendship points you get everyday when you talk with her.
The ranch girl likes animals a lot, so you impress her by showing her all the happy livestock you have, winning competitions with animals and riding horses around.
The mayor in town values hardwork, so the more you ship and the better your stats develop, the more impressed he is with you.
You can even a gold differ that digs you the more gold you have.
Gifts merely change the outlook some character has on you favorably, so talking with them yields better results, instead of being a flat bonus. However, gifts have a cooldown so you can't spam them and to keep the character's attention, you'd need to do other stuff, like doing chores for them, going on dates, etc. Simply chatting up reduces the rate at which their favour drops.
If your game has skills for a lot of stuff, use that as well. Count it as knowledge about specific topics and talking with anyone can be generic chit-chat for a regular conversation or you can pick a topic and, depending on how proeficient you are in it, you'll impress the person you are talking with.
Also, make it so the town changes around based on what everyone does, not just you. Every villager, especially the girls, should have goals and objectives they strive for and you can help out if you want to, earning the benefits of whatever they get done as well as friendship with them.
Like cleaning the woods, planting flowers somewhere, taming a wild animal, re-building a damn or a broken house that a storm crashed, find a lost item, help someone that's going through an harsh moment, etc.
Dynamic oportunities that make the town feel alive and work better than generic radiant quests.
You'd do this and instead of a game full of shallow basic bitches that crave the D based on how much of X stuff you've given them, you instead get a game where your waifu just wants to see you improve and become the man she knows you can be.