Questions & Answers about Han försäkrade mig om att ursäkten inte var påhittad.
Why is the verb var in the past tense here when the excuse itself is probably still a lie?
This is called backshifting. Because the main verb försäkrade is in the past tense, the verb in the att-clause is also shifted to the past tense (var instead of är). Even if the excuse is still fake right now, Swedish matches the tense of the reporting verb, just like English does.
Why is the preposition om included before att?
In Swedish, the expression is försäkra någon om något (to assure someone of something). When the "something" is a full clause starting with att (that), Swedish keeps the preposition. So literally, it translates to "He assured me of that the excuse was not made up."
Why does inte come before var in this sentence?
This clause (att ursäkten inte var påhittad) is a subordinate clause. Remember the BIFF rule: in subordinate clauses, sentence adverbs like inte must be placed before the first verb. If this were a main clause, it would follow standard word order: Ursäkten var inte påhittad.
How does the word påhittad relate to the verb hitta (to find)?