Is it normal to have a difference of opinion or disagreements about certain things in a relationship with my girlfriend? Is that considered healthy or is it bad?
Disagreements in relationship are normal because no two people are exactly alike and no two people see the world in exactly the same way. No matter whom you are with, you will have differences of opinion. And this can be a good thing. When someone else sees something differently than you do, they can offer you another perspective, and you might learn something. Imagine being with someone who never challenged you, who agreed with everything you said. Life would be boring! So when your girlfriend has a different opinion about something, listen to her! At least consider it, and at least acknowledge that she is entitled to her opinion, whether you agree with it or not. And she should also be willing to listen to what you have to say and acknowledge your right to your opinion.
That being said, however, there are certain things in relationships that cannot be compromised, and these things might be different for different people. For example, say you want your girlfriend to promise that she won't sleep with anyone else while she is dating you, but she wants to keep her options open. Here you have a difference of opinion on whether you want to date exclusively and be monogamous. This would be a deal breaker for most people because there could be no compromise for a difference like that. Some things that are deal breakers for me are smoking and substance abuse. I would not be able to tolerate a smoker or a man who abused drugs or alcohol. So these are such huge differences that I would not be willing to compromise. You should know what your non-negotiable things are when you are considering a relationship with someone. Know what you can tolerate and what you can't so you don't waste time in a relationship that is just going to cause you pain.
You see the difference?
Thanks for writing and asking such a great question.