BIB - It is, yes, but that's not the reason. Sinead appears to me to be Teacher's Pet, and must be featured as much as possible at all costs. They won't want her to be tied to an 'old man' when she could be having all sorts of shenanigans with all and sundry.

You'd think she'd catch on that her perception isn't that spot on after the Sinead katy disaster but clearly not...

Well I think that that is the reason that she does believe finn, because she didn't believe sinead when she was telling the truth so she doesn't want to make the same mistake twice

And not having picked up on the fact that it wasn't playful banter but one of the students at the School she worked was being bullied to the point of suicide and her daughter was the principle bully.