I forget the name of the bias/fallacy, but it's something like "I love and support X. If X is bad, then I support something bad, then I'm bad. Since I'm a good person, and I support X, then X must be good or I wouldn't support them"

It's probably a quirk of how we make decisions - we don't consciously make decisions. Instead, we might weigh out the options and that affects our choice, but in the moment we choose subconsciously. It might feel like we made a decision consciously, but sometimes at the last second we deviate from the course we chose (or upon choosing, realize that despite our thoughts we actually have already made up our mind otherwise)... Then we have to rationalize that choice, or start down a long and challenging road of constant introspection