Well mostly it's always us getting bored or not liking the plot/art/growth and stuff. Mine is this one time I dropped a yaoi bcs I hated the ukes thick eyebrows I also dropped KS cuz it gave me anxiety idk lol
If I think one or both of the leads is ugly/not my type. Also if I'm about to spit out blood cultivation style in anger over the miscommunication or denseness of the MC/ML reply