Said gently:
Could it be that part of you wants to believe you are partly to blame...
...Because if you are partly to blame for HIS alcoholism, then you must also be partly the SOLUTION to HIS alcoholism, goes the logic...
...that there MUST be SOMETHING you can FIX, to help HIM fix his alcoholism, goes the logic...
And if you decide you are not the root contributor to HIS alcoholism, then you know there is NOTHING you can do, to fix it.
You see, underneath this self-blame thinking lies a fantasy that you hold the golden key to fix his alcoholism, and to make the dream come true you only have to fix what you are to blame for.
CLMI