Hello r/mentalillness !

I am fairly new to reddit so I am not too sure if this is the right place to post this.

*If you have any ideas/advice/tips for me, please help me!! This is driving me insane*

The reason for this post is that I hope to find some people to give me advice on this topic which is slowly making me go crazy and killing my relationship.

As you can read it in the title, I have an extremely big problem with my girlfriend smoking. Sure, I think most people dislike their partner‘s smoking habits but in my case it is a bit more extreme.

**Background:**
I am 19 years old and in a great relationship with my girlfriend of 17 years. We love each other very much and I am having the best time of my life so far. When I met my girlfriend 1 and a half years ago, she just started smoking. Not excessively much but around 5 cigarettes a day. At the beginning I did not care that much and once I even bought her a pack because she was underage and struggled to get some. (Which I regret doing very badly)


**Fast forward to today:**
My girlfriend stopped smoking half a year ago for me because I started having a big problem with it. So whats the problem? The problem is that she still smokes on rare occasions like parties or evenings out with her smoking friends. 
I am extremely grateful and proud that she stopped smoking just for me and try my best to show her how much I appreciate it. 

The hate of her smoking grew over time to the state where I was close to simply ending the relationship. Although she smokes very rarely (like once or twice a month) I have a huge problem with that. Every single time we argue about this topic after it happened. 


**The problem: **
I really don‘t understand why this is such a big thing for me. It is driving me crazy. After it happened, I feel very depressed and can‘t stop thinking about it. I get so sad that I could start to cry any second. I think about the relationship and ask myself whether or not it is worth the pain. I think that it would all be easier to simply end it (we nearly broke up 3 days ago because of this). I thought about attending therapy but I just could not overcome myself to do it. I even thought about hurting myself.

My girlfriend wants answers. Why do I have such a big problem with it? Why do I still care so much although she only smokes so rarely? 
I don‘t have answers but I always tell her that it is because my whole family are smokers and i really f*cking hate it. I don‘t need another person smoking close to me. But I start to feel that this is not the true reason, but rather something deeper.

Additionally I feel like it is very unfair of me to control her life like that. She is young and wants to try things, I get that. But no matter how much I try to ignore it, it never works. I hate giving her a hard time and make her regret it when it happened but I just can not control myself enough.




**My theory:**
I heard about people having extreme fears or issues with ordinary things as a result of a trauma or bad memories from the past. (e.g. fear of snakes after being abused as a child, snakes=male genitals (not me))
What if my smoking girlfriend is not the problem itself but much more a symptom from a past trauma? What if my brain connects my smoking girlfriend with a memory of my childhood (I did not have the easiest) which is suppressed  to process it?
I don‘t know, I am just VERY desperate for answers and maybe curation.
I feel like this is the only problem we have in our otherwise very healthy relationship and will soon lead to breaking up with the love of my life.


So PLEASE dear reddit community, I am desperate for help and advice. If anyone is willing to help, I would appreciate it so much!!
It is killing me and my relationship. I can‘t live like that any longer without having answers.

You guys are the best!
Thanks 


Edit: I also posted this in r/mentalhealth simply because I hope to reach more people who could possibly help me.