If your spouse is having a bad day, reach out with love. Tell them, with words, that you are there for them and for anything they need. Then let them choose what would help the most. You might offer a few options of things that you know have worked in the past.
“Do you want to talk about it or do you need some space with a nice cup of tea, or is there something else I can do to help you now?” “Do you need some ‘me time’; I can take care of the kids for this evening.” Whatever the answer is, do your best job of being supportive.
If you are the one having a bad day, let your spouse know what they might do to help you work through it. “I’ve feeling stressed. Can I talk about it?” “I think I just need some alone time. I’d like to take a run. Can you hold down the fort for 40 minutes?” “I just need a good laugh.” “I want to vent; please just listen, no solutions or ideas. Thanks.”