We both began dating at 25.
setting aside everything else for a moment - it is not unusual for people in their 20s to have multiple relationships versus one long term for life experience. forever sounds good and romantic, but in reality young people grow and change and change their minds and their perspective.
she was drinking to excess when you met. so the "problem" preceded you. in spite of all your efforts to stem the tide, the problem continued and progressed. first trip to rehab didn't fix it.
now after almost a year in a protected sober environment, she has changed her mind. she spent 1/3 of your entire relationship "incarcerated" to prevent her from drinking. we can't blame her choices on alcohol. this is her at the most sober she has been since you've known her.
whether or not she is making a WISE choice is irrelevant. it is still her choice.
is it fair? nope. does it feel good? nope. is it life? yep.