I'd agree that the state should not be infiltrating non-violent activist groups. But the fact that he was an agent of the state doesn't seem to be the focus here.

"He wasn't the man I thought he was" is the sort of thing that could be said after practically every breakup of a relationship. Some times more than others, but trying to put some sort of line past which it is rape is not feasible - not, that is, if you are in favour of the rule of law, rather than people being sent to prison based on personal moral judgements of juries or judges about exactly how disgusted they are about someone's behaviour.