I agree with everything Barrister has said. I will add that men forget that it is ok to disagree with a woman about something, and LEAVE IT AT THAT. This was hard for me to learn. Partly because of training from our mothers, and partly because women REALLY can't leave a disagreement alone - they MUST have resolution, and in 99% of cases, the only acceptable resolution for them is their "winning". If they don't have resolution/agreement from you, they get very anxious and can't calm down very easily or quickly. But you have to remember - that's their problem, not yours. Saying you are wrong or agreeing with them about something you don't actually agree with just to "save the peace" is the worst possible thing you can do. It lowers her respect for you and it will be used against you in all future discussions. The argument frequency will increase as well.
I do feel it is very important to listen to your girl express what she is unhappy about, and you should do it openly, receptively, and with full attention. Acknowledge that her FEELINGS are valid - don't claim they aren't. But if you disagree with her, without arguing or being combative, you simple state YOUR feeling and position on the matter and explain that you understand she feels differently and you both have a difference of opinion on it and that's ok. 99.999% of the time she will immediately start over again in an attempt to circle repeatedly on the subject until she wins, and from her first attempt to circle, this is when you shut it down, politely. "Baby, I already know how you feel. You explained it to me and I listened to you and heard you, but I also explained how I feel and I feel differently about it. No amount of further discussion is going to change either of our minds, and we will have to simply accept that we disagree on this, and that's ok. Arguing is just going to make one or both of us madder and drive us further apart. I'm not going to do that, so the conversation is closed. If you can't handle that then I'll head out until you calm down." Of course, she will HATE this and claim your shutting the conversation down is absolutely tyrannical and worse than arguing but you will have to believe and trust in the red pill on this one. Yes, it will upset her, but if she is not a nut-job or narcissist and she likes you, she will get over it and the outcome will be preferable to endless arguing, or you caving to something you don't agree with. If she can't get over it, then she is crazy and high-drama and not relationship material so you next her.
My GF still complains from time to time to me about how I handle these things - "I feel like everything is your way or the highway and if you don't want to talk about something you just control the conversation and shut the conversation down!" Yet she is MADLY in love with me.... and her statements are false because:
1. It isn't my way or the highway. When I feel she is right about something, I have apologized.
2. I don't control the conversation - I listen to her and ask her questions to understand her. Then I say how I feel. The only "control" I employ is refusing to fight. Sorry not sorry. I know full well that shutting an argument down is 1000x better than arguing for hours and never getting a resolution anyway.