The phrase "affair for which" is correct and usable in written English.
It can be used when referring to a specific matter or event that is being discussed or questioned.
Example: "The affair for which he was criticized was a result of poor judgment."
Alternatives: "matter for which" or "issue for which".
He said Sarkozy had not been placed under investigation in the more serious Bygmalion affair, for which he was given the status of a legally assisted witness.
The affair, for which they expected a big turnout, was scheduled to take place at two o'clock on a Thursday afternoon in the lobby of the Kyoto Hotel.
Over the years, in absentia and in person, Gelli was tried and convicted in Italy on various offences, including fraud relating to the Ambrosiano affair, for which he received a 12-year sentence in April 1998.
As he says, he has lived his life publicly; writing, on the contrary, is "a secret vice, a sort of clandestine love affair, for which [the writer] preserves his moments of humanity".
Especially if it's been a fancy affair for which you've travelled from afar and arranged overnight accommodation, bought a new outfit, a present and been on a hen or stag do.
(Only in a footnote does Mr. Giddins acknowledge "that he cheated on Dixie during the 1940's and after, embarking on a love affair for which he almost cashiered their marriage, we shall see in Volume 2").
As Golding would be the first to attest, those round-the-world races are predominantly downwind affairs, for which the water-ballasted, canting-keeled 60's were created.
The flourishing French culture and spirit in Quebec was seen not as a matter of diplomacy or of commerce but as an issue of cultural affairs, for which Quebec had already set up a government ministry.
In 1968 he returned to the Foreign Office to deal with defence and especially nuclear affairs, for which his intellect, his knowledge of the Soviet Union, and his experience of the military particularly fitted him.
He went on: "The year has also one of a crescendo of criticism of the court from many quarters in the United Kingdom, in which it has been accused of inefficiency, incompetence and meddling in affairs for which it was not created".
Now, presumably not all moral states of affairs can be justified: eventually there will be basic moral states of affairs, for which no justification can be given.
