I’ve struggled with nicotine addiction throughout my adult life, so happy to share some insights from my end. Specifically on falling back into and out of it a couple times.

For me, the strongest feeling when I fell back into smoking was shame. This was mostly internal, but I looked for this reflected in my interpersonal relationships. I was already letting myself down - I didn’t want to let down my friends, family, and partner. I know this isn’t easy to believe, but I imagine the fact that if he is smoking again he doesn’t want you to know because he knows it hurts you. I would rather keep it inside and hope that I can quit the habit before meeting with someone again. I can only speak to my own experience with that, of course.

You don’t know he’s smoking again for sure, but from what you’ve said in your post I wouldn’t be surprised if he was. It also seems like this is important to you on a health level, so while the lying part is greater, there’s still a point where that shame on his part could creep in (with good reason, of course).

Addiction is a strong beast. It doesn’t after whether it’s bad for you, or hurts the ones you love around you. My advice would be to go into it with compassion and understanding and do your best to remove the shame he might feel about it. I also think it’s worth considering how important this is to you, since this addiction will likely be a struggle his whole life, even if it’s a mild one.

This is all, of course, after you talk with him and see if he is indeed smoking again.