I Just Had To Deal With Other Fans Pushing It On Me In The Past - Tumblr Posts

Reasons why someone may not like a ship without having moral beef with it:

The writing in canon was badly written.

The fanon for this ship mischaracterizes one of them in a way they can't stand.

They hate the character designs, and/or get eyestrain from them standing next to each other.

They hate one of the tropes used in the ship.

Making this ship happen would go against their headcanons.

They don't like the arc/story beats where this ship got content.

They don't like one of the CHARACTERS.

All the BNFs ship this, and they got tired of it.

An absolute jackass shipped this, and the ship was tarnished because of that.

They haven't gotten to the point in canon where they met.

It reminds them of a past relationship, and in a bad way.

They prefer another ship.