Boyfriend nicotine withdrawal causing all types of emotional symptoms?

No , don't do that,[ cigar in mouth trick],
The trouble is, hes only cutting down and not stopped yet. [in no mans land]
When you stop , the physical symptoms don't last very long at all [less than 2 weeks] that could stop him.
But the emotional ones are there for, up to life term [regressing all the time] and that's what needs to be worked on with awareness constantly. This would not be so draining as the physical slow withdrawal signs of "pain in the butt man" you have right now .
Go the whole hog and get him to give up total if he dares. Best for you both and all of us. Good luck.
ps....show him this if you want

Sounds like me when I tried to quit. No one else could stand me and I couldn't stand me. I don't deal well with withdrawal, and since I have Bipolar 1, I would get more and more depressed and irritable the longer I was off them. I would even get suicidal. Of course I would have to cheat, which would only prolong the agony. I got to the point that all I could think about was having another cigarette. If I did, it didn't stop the cravings or depression or irritability. I was damned if I did and damned if I didn't.

Years passed like this. I got emphysema. Then I started on CHANTIX, a new quit smoking aide that actually takes away the craving. It chemically binds up the nicotine receptors in the brain, making wanting that next cigarette moot. It's cool as hell. One day you're a smoker, then the next day you are among the living, resenting all the clouds of cigarette smoke you have to walk through. Within about 3 weeks for me, and it worked through thick and thin. (I have emphysema. Loved smoking. Had started to quit and my sister committed suicide, then my mother died 2 days after I told her, and I wound up in hospital with double pneumonia. Still took my Chantix everyday. I was done three weeks later. Some take 6 weeks, some 6 months, but Chantix breaks that craving created by the patch or gum or cheating.
I kept a dozen or so to help me through any rough patches down the road, and invariable just had to take one and it would pass.

It's not cheap, but neither are cigarettes or pneumonia or emphysema or cancer. You have to get it from your doctor, and it can have some side effects. But most people can use it. Get him to look at this and give it a try. I swear within 24 hours of quitting he will feel way better than he does now.

Here's wishing the best to you. Bless you for trying to help him quit.