I agree with you: it looks like Faulkland doesn't control his emotions at all and gives full reign to his (ill-understood) sensibility. As far as I can describe his thought processes, the first time his neurones make a click, an idea springs to the front lobes, all ready. And as the neurones click (in a sense) randomly, so...

Every one of his friends describe him as capricious (Jack to his face, Lydia to Julia). It is well-known, then, but I feel with them that there is nothing to be done.