Actually, it's not a big deal for me, since I don't Self-insert as the protagonist. But I don't like it when a yandere character hurts the female lead and causes her real physical harm,that kind of thing. Still, it is just a game, so it's okay to have that too. I just hope there are multiple endings,for me, that kind of harm would count as a bad ending.
I actually quite like yandere characters in games, novels, or movies.If I ever encountered someone like that in real life, I'd stay as far away as possible.