This has never happened to me with someone beyond a stranger. This is unacceptable behavior from a stranger. I’ve only given people a pass if they don’t understand I have a stutter due to my techniques I use to cover, so they treat me like a ‘normal’ person and tease me if I trip up. Hopefully your ‘covert’ status means your boyfriend does not consider you a stutterer and thought you were just flustered in an argument. If they did understand I have never had to deal with someone in my personal life who acted that way.