The human mind is capable of a lot of magical things, so you're not alone when it comes to spiralling. Pardon me for asking, would you be able to clarify what you meant by "disagree on what being good actually looks like"? By being good, do you mean towards each other, or to someone else, or just personal taste in certain events/objects/opinions? I feel the definition of "good" is very subjective, and it's dependent of each individuals personal history and experiences with events. For example, people growing up with potato chips will see it as "good", while those who do not may not see it that way. Even though nutritiously it is not good (with lots of oil and carbs), but because the person had it for a long time, they deem it to be "good" for them.
It is true that disagreements are normal in a relationship. Whether it's as you said, not emptying the dish washer, or leaving clothes on the floor, it can vary between the small little things, to the very large ones like political stances, or religion. It is up to both of you to decide what are the deal breakers in your relationship, and what are things you can work on.
I feel the best way to work on this is to verify each other's core values. Not all core values have to align with each other, but a majority of them should, and the rest are things that couples will learn to accept or work together to come to mutual terms. Relationship is both about appreciating a partner's good points, and also accepting their weaknesses with kindness, sympathy, and care. Also, know what are deal-breakers for you in a relationship (what can you accept, and what can you totally not accept). For example, a deal breaker for me is if my partner forces me to become a vegan. It's a deal breaker to me because I'm a heavy meat eater and love eating meat. But if my partner can accept that I'm a meat eater, we can still both be in a relationship with this difference, while also sometimes compromising to spend time together (she can take me to a restaurant that sells meat, and have a vegan dish. Or I can join her with her vegan meals some times).
Hopefully that helps Maryblue, happy to chat more too.