Totally agree with Pax. If you're close enough to be having sex with someone - close as in close physical proximity - you're close enough to get lots of things from them, including corona virus, a cold, the flu, strep throat, a bunch of different upper respiratory infections, etc. The corona virus is not sexually transmitted like chlamydia or gonorrhea is.
Wash your hands often - not obsessively, but often, stay home when you're sick, clean items you touch a lot (your phone, for example), don't touch your nose, mouth or eyes. You may still get sick with something, but you'll reduce your chances.
If you mean the new virus originating in China, currently it is believed to mainly be spread the same way as other corona viruses such as the common cold, which is getting coughed on or coming in close contact with someone who is infected. Because it takes about 14 days, they think, for symptoms to show up, it is possible to get it from sex not because it's sexually transmitted but because the person you're having sex with has it and you're in close contact. Viruses are insidious, you really can't avoid them because you have no idea if you've been around one. Influenza kills a lot more people every year than the corona virus is likely to. If you're looking for life without risk, this isn't the world you want to be in, so best to take the recommended precautions but not let it ruin your life by obsessing over it.