To stay on yours and the other person's better side.

It depends on the context too, whether these two people cohabit or have to work together.

It may also be that when they are in the presence of that other person they do not inhabit themselves completely. In "real-time" they may be adapting to the other person, because they feel they may not be accepted if they were to be themselves. Reflecting on that in hindsight may cause the irritable, contradictory feelings - the ones they reveal to you.

Ethical types may make more concessions and be aware of the contradictions; that they relate to a person in some ways, but not in others.
It seems important to find ways to cooperate with others and to learn to accept them as they are, but what happens in the middle can be messy and imperfect.