An aside that occurs to me here, where does this whole "realistic = bad things" idea come from? It's not like romantic relationships and nice things don't happen in real life or anything. People have happy, lasting relationships. People make sweet gestures and can be funny or happy or lighthearted.
I think when a lot of people say "I want more realistic stories", they don't mean they want stories about breakups and arguments and tragedy, per se. Those make for interesting stories, but my thought is that what people want are relateable stories instead. Things that could actually happen, but not necessarily downers. Maybe a little more complex than "Schoolgirl A meets Schoolgirl B via some contrived event and it's love at first sight", maybe a little closer to people's lives so they might be able to imagine themselves doing stuff like that too. Look at Off Time by Morishima Akiko. It's sweet, it's happy, it's realistic. In the relateable sense, that is.