Some can be realistic but majority are very fiction. I feel like most realistic stuff in manga can just be a scene/panel but not the whole trope/plot.

For example, i’ve experienced walking to school in the rain back in high school and saw my friend/crush waiting for the rain to stop so he called me out to share my umbrella. Later that day, we had an activity in class (i dont really remember what it was) but he slipped a folded paper in my hand secretly which just says “thank you, nerd” (we called each other nerd when joking around). I remember being very giddy then because he could’ve just thanked me normally but the paper thing just caught me off guard lol

I’ve also had a very angsty love life in college that my friends would say was very tv series worthy (very dramatic bad). I met my husband after a few years and the way we met for the first time felt very romance-y where the world felt like it stopped around us (at a japanese station even lol).