Question

"oh the affair was quite above board, my love I assure you, my love!" when does john say this and why??

Answer 1

This sentence is having two meanings.

Now if we talk about the first one, which indicates the affair and flirtations between John and Laura Hinkle. John tells and assures his wife regarding the affair with Laura. He told that was only during the time while they worked together in Ouija Board. There is nothing beyond that.

The other thing is between John and the Ghost, Helen. Here by 'Above Board' John meant that the whole relationship was absolutely normal. There was no bad intention from anyone.