I think it's fairy obvious since F is launching a new podcast that there was some kind of falling out with Brid. Fionnuala left first, ifrc, leaving Brid sort of in shock. Brid would have been pregnant at the time and has since upsticks and moved to Wexford so I'd imagine the shtick she feed about being too busy was a lie and she just didn't want to run the podcast remotely with Brid and perhaps there was a falling out. I always forget how young fionnuala is and maybe her pal having a baby and such a big change in lifestyle was too much for her and it didn't fit the image she's trying to create for herself. She might regret it down the line.