***Need relationship advice..adults answer only please..WHAT'S YOUR OPINION?

Hi there...26yr.old female here..My situation is that i have been in a relationship with my bf for almost 4yrs. and he is a seriously addicted smoker. He smokes newport cigs as well as weed every single day that i have known him. I do not smoke either and have never smoked a cig or weed with him EVER. I have smoked cigs in the past..when i was a teenager, but have grown out of that bad habit and just find it nasty, un-healthy and STINKY! Anyways..the first year we were dating i never complained or said anything really...cuz i knew he enjoyed it and it was a habit of his so i didnt want to say anything and pick on him. I believe everyone should be able to do as they please and what they enjoy doing. But for the past 2 yrs...it has really been bothering me. Everytime im with him he is always smoking..all day and night.I try not to nag..but i say comments like...i hate breathing that in....or...its really un healthy and i dont like it...or IT REALLY STINKS...i cant stand it. I dont want to nag him or annoy him..but its really starting to bother me. He says all the time....i tried to quit babe....but its really hard. I try to be understanding...but i just think its an excuse or something. I understand its addictiave...but i wish he would just understand that i cant stand being around it...the smell of it..or inhaling it...and as long as im with him...I WILL ALWAYS BE AROUND IT...:( i honestly think ABVIOUSLY he really enjoys it...BUT IS NEVER GOING TO QUIT :(...so that being all said...i tell him all the time that i would be supportive if he would try to quit...but he just says its hard...and keeps smoking weed and cigs everyday. I love him SO MUCH! and i dont want to leave him over smoking...his family even got him the eletronic cig...but he doesnt use it. so....ANY ADVICE....PLEASE no rude comments...if ur a smoker...im not trying to offend ne1. just my own personal opinion. please....HELP. also...i really worry about his health...and i tell him that...but he said he doesnt care really about his health. and also his grandpa died from lung cancer.