One of the nice things about marriage is the level of comfort you achieve with one another over time. You can feel so relaxed with this person. You can really "let your hair down" whether that is lounging around in your sweats or sharing some of your worst fears.
You can share your deepest confidences. You can tell him how hurtful your Mother has been or how your best friend hurt your feelings. You can tell her how your best friend hurt you when he left you out of the golf game and how hurtful that was or how disappointed you are with your son's college choice.
You trust this person to always be there for you. If you want to leave your job, he will support you. If you want to start your own business, she will work with you side by side. If someone insults you, she will have your back.
However, with this very special closeness also comes irritations. You don't like how he loads the dishwasher. Or he doesn't like how loud she has the TV. When you want to do a project together, these differences get in the way. Many couples start correcting each other. You want the other to do it your way.
Unfortunately the comfort level and trust take a back seat. Spouses begin to ask "why are you doing it that way?" or say "we don;'t really need such an expensive cabinet."
When you choose to do a project together it is important to define the decision-making process. Discuss how to negotiate the decisions. Negotiation should be an easy process when you are so connected to another person, but the problem is that each wants it done their way.
If you ask her to research new flooring for the house, then let her do the research and get back to you with the information. Don't micro-manage. If he is supposed to check on airline prices, then don't change your timeline or be too impatient and step up and take it over.
In other words, when you agree to assign a task to the other, then let go. Determine your deadline: when you would like the answer and agree upon that date and time. Then stay out of it. if you don't like the end result, then negotiate that, Don't just argue or demean the other person.
Working together with your favorite person to create something special can be rewarding. Work at it so that it is also a smooth process. Keep your distance. Stay out of each other's space until you have the data and are ready to negotiate the outcome.