As much as I enjoy Masizu as an option (though second to Kotoka), I imagine living together would eventually get super annoying. There would be no way to have a normal conversation without her getting super turned on mid way unless you spoke through a voice modifier or used sign language. That means doing pretty much anything as a couple involving friends or coworkers, like going to dinner, having a party, etc would be difficult. Tatsu could only speak sparingly, if at all, in the presence of Masizu, or risk getting into an embarrassing situation.
Just imagine how awkward it would be if they ever had a kid. The 3 of them eating dinner, and the kid asks Tatsu a question which requires a bit of explanation. Mid way through Masizu would leave the table (so she doesn't start acting like she is in heat in front of her kid). Now the kid asks why Mom always leaves once Dad starts talking. Does she dislike him? Are they fighting? Now Tatsu has to explain that his wife leaves because him speaking is alone powerful enough to bring her to orgasm, which she does not want to do in front of her kid.