Is it possible to be immune to cold sores?

So my SO gets cold sores when he’s stressed and i know it can be transferred to me if he Kiss right ? Or at least I thought ?? This is his 3rd outbreak since we’ve been together and every single time he’s had an outbreak we’ve had a slip up and accidentally kissed/made out. It normally always has been a make out cuz it’s when we’re having sex and werein the moment so we forget. I have yet to get any cold sores though. Right now he has an outbreak and we’ve been kissing the whole time and making out. So am I immune to it? I’ve always had a strong immune system and never get sick but I thought I’d for sure get them by now ?? Side note: I know for a fact I’m immune to poison ivy and i know that has nothing to do with cold sores/herpes but still That’s why the question is on my mind.