Stress also strains communication with others, you feel irritated, you think the world is not understanding you, you start getting frustrated over petty issues etc. You just can not demand and expect the other person to go mood-swinging the moment you do. So just try and control you stress. Start talking to each other and let your heart out.
So the next time you find your sexual life going haywire, just relax and understand your spouse's issue, if they have. Sort it out so that you can have and enjoy your life.