The story is about a planet where a robot named the matchmaker has taken over society and kills people if they don’t find a partner. Both the Doctor and River show up to investigate. The Doctor tries to legally match up with an asexual woman so she’s not murdered but can’t because River has tampered with the computer system so it shows her as his wife and makes him unavailable to anyone else. When the Doctor rejects her, River is very offended and upset the whole time. He is very adamant he’s not interested in being her wife and doesn’t like how she waters down the word and masquerades as such. Asking “do you know what that word means”. Later on, the Doctor tries to make the robot scan the asexual woman and recalculate whether a partner would make her more productive. It doesn’t work because she’s alloromantic. River says it’s the Doctor it has to scan because he’s the one with no romantic feelings whatsoever. He agrees. It scans her. It works. The robot shuts itself down.

But here’s the thing. The robot was taking a moment to moment scan. In that moment the Doctor had no strong memories or current feelings of romantic or sexual love. That does not disqualify someone from being Demi or Grey Ace. It was a moment in time. Him having no attraction to River whatsoever does not prove he is Aroace in the sense of being someone who will never experience sexual or romantic attraction. It just proves he didn’t feel those things for River. Having a stranger tag you as their wife in a database and get mad you’re not happy about it is really quite the ick regardless of sexuality anyway.