From Longman Dictionary of Contemporary Englishthe truth/fact of the matter is (that)the truth/fact of the matter is (that)spoken used when saying what you think is really true concerning a situation The truth of the matter is that we don’t know exactly how the disease is spread. → matter
Examples from the Corpus
the truth/fact of the matter is (that)• For the fact of the matter is, all the fight has been taken out of Blue. 