Hi Jessers - so glad you found the forum in your time of need.
Sometimes there is a good reason when "no one understands". It's because we are seeing something through a lense of what we want it to be, rather than what really is.
I went through something very similar in 2011. Guy I had known since high school. Whirlwind romance. He held it together for about 4 intense weeks before I began to see the cracks. The story is around here somewhere but I neglected to add a number of key pieces. I was pretty surprised when I went back and read what I had written. Oops, forgot to mention that he bought coke within a few days of coming to stay in my home. Oops, forgot to mention that he paid just $35 for that coke. Oops, forgot to mention that you can't get coke on the street in my town for $35, that would probably be crack. (I asked around, definitely not familiar with the street prices of anything anywhere.)
I came here a posted that he had an alcohol problem. I have no recollection of why I left out the rest. I suspect I was just too beaten up after the family situation I had been through and maybe I was just completely disgusted with myself for ignoring some rather major signs and putting an active addict in the path of my beloved brother who was in the midst of a major life or death struggle with addiction.
Reading as much as possible here on the Friends and Family forum will give you a good idea of what you will experience in the future if you continue your relationship with him before he finds recovery.
I'm sorry you are going through this. I know how hard it is to find someone with which you can really connect.
Peace,
Hanna