Konnichiwa Fixelbrumpf-san!
Yes, "Tsujituma" is "coherence" or "consistency". But what is it concretely?
An instance... there are two people A and B.
A said : I have a summer house and cabin cruiser in Japan!
B said : Really? Great! Please invite me to your summer house, and let's enjoy cruising!
B was very excited, but it is a fabrication of A. A told a lie out of vanity. And A can not invite B because A has not a summer house and cabin cruiser. But A can not tell the truth, because A has great pride. In order to cover up A's lie, A has to lie still further.
A said : Sorry, summer house is being rebuilt now, and cabin cruiser had sunk... yes, cabin cruiser was sunk by typhoon and summer house was damaged by typhoon too! and summer house is being rebuilt now!
Of course it is a lie too. But A must tell a new lie in order to cover up A's lie that is "I have a summer house and cabin cruiser in Japan!".
In this case, new lie is called "Tsujitsuma awase no Uso" in Japan. "Uso" is a lie. "Tsujitsuma" is "consistent".
What is "awase"? It is "awaseru" originally. "Awaseru" means "fit" or "adjust". "Tsujitsuma awase" means "adjustment for consistent".
In "ツジツマ合わせ別にいらない", yes "別にいらない" means "I don't need ...". And "ツジツマ合わせ別にいらない" means "I don't need the reason(or lie) to cover up contradiction". And it express "I live honesty".
Please decipher my poor instance.
Believe In Wonderland! NANGI