Unrealized expectations lead to disappointment and frustration and ultimately resentment. The fewer unrealistic expectations you have about marriage and each other the better. Expectations in areas of how you talk to each other, treat each other, stick up for each other, spend time together, show love and respect, etc.
When you don’t have a long list of expectations, then you are disappointed less and delighted more.
Having expectations for a marriage is reasonable, as long as they are realistic. Share with each other your (short list) of visions for marriage and for the other person. Make sure you know what your spouse expects from marriage and from you. And live up to those expectations.