If he gets it in his system you’ll get it. But if he just gets it on his skin or his clothes there are ways to prevent either of you from getting infected. Make him strip as soon as he gets home from work and quarantine his clothes. Assume they’re infectious for 1-3 days. Have him shower as soon as his clothes are off before he sits down. He could have the virus on his face or neck or arms if he wears a short sleeve shirt.

You could each make an effort to disinfect his car after he uses it for work. Steering wheel, shifter, radio buttons, seat belt, etc.

The more shit you disinfect, the less chance he’ll get infected by touching his own mouth or nose or eyes.

Consider going out with him and buying a mask he can wear at work. A lot of people are making their own. Also winter outdoor stores have face protection, Muslims have those things they wear, a bandana if his work will allow it. Whatever you can do. Because if he’s in a crowded area, the coronavirus is floating around in the air waiting to infect somebody. It can float there up to 3 hours. Keeping your nose and mouth covered is the best protection in that crowded space.