Having expectations isn’t the problem, insisting that your expectations are the right ones
is the problem.

It’s completely normal to come into marriage with expectations. Expectations about roles, chores, decision making, parenting styles, vacations, etc. The thing is, your spouse also came into the marriage with expectations, and often, not the same ones. Even if you have many things you agree on, it’s inevitable that your expectation and your spouse’s expectation won’t line up. At that moment, when you realize you and your spouse don’t agree, first, stay calm. Our tendency in that moment is to feel threatened. Sometimes to a greater extent, sometimes to a lesser extent, depending how big of a disagreement you are having, or how important the issue is to you. The reason that the first to work on is staying or getting calm is because when we feel threatened or distressed, we don’t think as clearly as when we are calm. Often, people think about solving the conflict as the way to get calm, but that’s backwards. Being able to think through and discuss things calmly with your spouse to resolve a conflict will have a much better chance if you first work on getting calm.
How can you do that with this distressing conflict still between you. First, shift your focus from your thoughts and pay attention to what the distress is making you feel physically. Take some deep breaths, breathing in slowly exhaling even more slowly to calm your heart rate. Once you’ve gotten a handle n your physical activation, you can switch back to attending to your intellectual thoughts. Reassure yourself that there is no immediate threat. The reality is that the moment you discover you don’t agree will likely not be quickly followed by having to address your difference in a practical way. There is almost always time, to talk, to explore different ways to manage or negotiate your conflict, before having to actually face the conflict you’ve realized you have. Take the time to do things right and discuss things calmly. Don’t compound the difficulty of having a conflict in expectations, with bad feelings from having a harsh fight over it.