Why? The missus should go anyway if she's had an unusual bleed in that area, and I'm sure the OP is perfectly capable of arranging a visit to a GUM clinic without her knowing. Divorce is only on the cards if it does turn out to be an STI.
Why ?, consider it artistic licence

Lets see where the thread heads eh ?
Not avoiding shagging as posted by @Jt a (schoolboy) mistake, sooo easy to come up with an excuse
The OP might be best served by getting a test privately for speed rather than a GUM
Soon as the window for doing this opens
As to how @aif handles the OH is another matter
Walking around on eggshells
& the xmas NY break means more time spent together than otherwise
Especially if the missus fancies a festive shag

@aif would be best advised to get a prescription at the same time as the test & take precautionary antibiotics to clear stuff out pronto these kick in fairly quickly
Then a new year shag [possibly earlier] could be roger roger got your vector victor you've got clearance clarence