I think it could be a neat aspect to the game. First off, in terms of the game, it doesn't really state how old anyone is. Sure, we all know the story, but you can change that to whatever you want. In terms of the art, some of the characters definitely look like they could be old enough to be in a relationship. Even if it's just a cute "boy-tries-to-impress-girl" (or vice versa) type of thing. This might be a lot of work, but it would be neat if (mostly) every girl (again, could be guys as well) in the game has a set of requirements you have to reach in order to progress the relationship. Maybe ones impressed by gym badges, maybe another is impressed with water type pokemon, etc... You could potentially create some new items, like flowers, chocolates, etc... And you just keep going back to the girl with "here's this" or "I did this". Which would allow you to progress to the next step. Maybe there's a reward for getting a girl, maybe that's the end of the game, finally impressing the girl of your dreams and it's happily ever after. Maybe she would get pissed if you keep bugging her without the next requirement. Could be something fun there... but quite a bit of work.