I noticed that too. When the text messages were first discussed...the "romantic relationship" was revealed at the same time. As far as I know, there has been no investigative reporting about their alleged "affair".
They sent over 50,000 messages, of which 7000 were released and the rest were "personal" i.e. sexual. Furthermore "...the department has redacted from some work-related text messages portions that were purely personal. " See https://www.washingtonexaminer.com/byron-york-justice-department-withholds-majority-of-fbi-texts
Why would there be?