jwpat7's answer is very good.
Just as an aside, there is one word for the “Honne and Tatemae” phenomenon, but it is pejorative: hypocrisy! A slightly less pejorative and more up-to-date word is spin. I do not know where the term originated, but let's assume for fun that it came from either public relations or politics. To spin, of course, is to put the best possible face on something embarrassing. As the saying goes, however, "You can't make a silk purse out of a sow's ear."
As far as a two-word answer to your question is concerned, I thought of the words diplomacy and honesty. In the “Honne and Tatemae” dyad, Honne would correspond to honesty and Tatemae would correspond to diplomacy. In analogical form:
Honne : honesty : : Tatemae : diplomacy.
There is a time to be diplomatic, and there is a time to be honest. When a wife asks her husband
"Dear, do I look fat in this dress?"
the husband is free to be honest and say yes if he thinks the dress does make her look fat, but he does so at his own peril! He is much better off saying either
"No, my dear, you look positively svelte in that dress!"
or
"To be honest, my dear, I much prefer you in the red dress. I find it kind of sexy!"
While a person cannot be brutally diplomatic, diplomacy can be overdone, particularly when many human lives are at stake, as when two superpowers are on the brink of war. Sometimes one has to hit the mule over the head with a two-by-four simply to get its attention!
Who knows what would have happened in 1962, for example, had President Kennedy not given the Soviets an ultimatum (the two-by-four) to get their nuclear missiles out of Cuba!
How did Kennedy respond to the Soviet threat of delivering more nuclear missiles to Cuba? Of the seven options Kennedy's advisors gave to him, he chose to place a blockade around Cuba.
What many Americans do not know (or choose to forget) is that Kennedy, in response to the Soviets' acceding to his ultimatum to stop delivering missiles to Cuba and to remove the nuclear missiles already inside Cuba, also agreed privately to remove American nuclear weapons from Turkey.
Here we have an excellent illustration of both honesty and diplomacy. What makes Honne different from honesty, however, is that the former is hidden or surreptitious--primarily, I assume, to allow each side to "save face."
One the one hand, Kennedy needed to convince the Soviets (and Krushchev in particular) that he was not going to take the diplomatic approach in solving this challenge to American sovereignty that was occurring a mere 120 miles from our shores.
On the other hand, he knew that he had to balance his apparent "tough guy" approach with a concession to the Soviets that would allow them to save face. Playing up his ultimatum and playing down his concession turned out to be a win/win for both America and the Soviet Union!
Neither the Soviets nor the Americans had any interest in starting a nuclear war, but they acted as if they did in order to get something from each other; namely, the removal of U.S. nuclear warheads from Turkey and the removal of Soviet warheads from Cuba.
In terms of “Honne and Tatemae,” the Soviets' outward and disguised reason--Tatemae--was to show America that they were just as free to place missiles in Cuba as the U.S. was to place missiles in Turkey. The Soviets' real intent--Honne--was to get the U.S. to remove her missiles from Turkey, not to start a nuclear war.
Likewise, President Kennedy's outward and disguised reason--Tatemae--was to stand up to the Soviets and show them that U.S. resolve would not be shaken. Kennedy's real intent--Honne--was to save face following several embarrassing incidents related to American involvement in Cuba's affairs (e.g., the Bay of Pigs fiasco; the Soviets' finding parts for nuclear weapons aboard an American naval ship; and the Soviets' shooting down of an American U2 spy plane that flew over Cuba).
The concept of face-saving may not be as inherent and as pervasive in American mores as it is in Japanese mores, but it still figures prominently in American diplomacy internationally.
Best Answer
Ipso facto would not make sense in your example, as there is no 'fact' referred to. Eo ipso there means 'in or by himself', which does make sense with the qualification in the next clause.
Eo ipso is not a phrase to be recommended (unless you are writing abstruse philosophy, in which case you need a considerably greater command of the language than a website can help with); on the whole, I would avoid it praeter necessitatem.