Why can't my husband relax a little ? ?

just because you are married doesn't mean that you have to do everything together. if it bothers you and him that much then take your own car to the store. start hanging out with your girlfriends. maybe he is that stressed out from his day at work, or dealing with something at work that is causing him to react this way at home. just because you two are married doesn't mean that everthing has to be about 'us' and 'we.' you two are still two different people, two individuals who merged your lives together. he still has his likes and and you have yours. maybe you two should have your own rooms as well so that he has his space and you have yours.