Loool anon. Considering Carson basically sees service as a form of personal redemption, I’m fairly confidant he hasn’t been with a woman since abandoning the stage (assuming he slept around during his time as a Charlie to begin with). I mean, he isn’t exactly the type to have sex out of marriage - that was basically established through Ethel.
And I really wouldn’t it put it past the war to be the burden of all his issues. This is the man who freaked out pre-war about the seam in William’s jacket. Carson is so dedicated to being a butler, so much of a caricature instead of a man, that when a war trivializes both his position and his standards, I totally expect that to stress him out to the extreme.
He’s basically Mr. Stevens in The Remains of the Day, but with some more emotion. And a singing voice.