The short answer to this question is, “It depends.” That is, it depends on what a good relationship is to you.
What is a relationship, after all? Isn’t it essentially a set of formal or informal agreements and expectations between two people about how they are going to act towards each other? That means that each relationship is different, based on the particular agreements and expectations between the two people.
I would say that a good relationship is one where both people are happy with the agreements and expectations between them and where both are happy with how well the agreements are kept and the expectations are met.
There is a lot of room for differences in that definition. In relationship A it may be fine if the two people don’t see each other for weeks at a time. In relationship B there may be a big problem if each person doesn’t call the other at least once a day. There are very different expectations in these two relationships, but as long as both people are happy, who’s complaining?
This being the case, you might think that the secret to happiness is sticking to relationships with people who have the same wants and expectations that you do. There are two problems with this. First, there is nobody in the world who has exactly the same wants and expectations that you do. Second, “opposites attract”, as the old saying goes, and most people end up in relationships where there are some significant differences between the two people.
In fact, in today’s world we are exposed to so many different perspectives, cultures, beliefs, and lifestyles that even the person you grew up next door to may have very different relationship expectations from you. You’re even more likely to have different expectations if you have different types of personalities, are different genders, etc.
That said, most people pick relationship partners who mostly agree about most of their wants and expectations. Nonetheless, there will always be some times when you realize that you no longer agree or have the same expectations about everything, or you realize that you misunderstood each other about some of your agreements and expectations. This is perfectly normal, and doesn’t mean the relationship has gone “bad”.
The health and happiness of a relationship comes from your ability to deal with the inevitable differences and changes in wants and expectations in ways that genuinely work for both of you. In fact, if the relationship is the sum of your agreements and expectations about how to be with each other, then re-making those agreements and expectations is simply how you keep having the relationship.
Seen this way, disagreements are not necessarily signs of something wrong. Rather, they are simply a sign that a relationship is happening!
Unfortunately, most people haven’t been taught how to recreate the agreements that make a relationship. Couples counseling can be a great resource for learning to do so.