There's a difference between being his girlfriend now ( which I have tried to make clear I am not) and removing all hope for the future (which runs the risk of him not staying in rehab long enough to get sober). Yes, it's still false hope, but if my status said in a relationship, it would imply I still AM his girlfriend.

Subtle differences, sure, but important ones at the moment, and made much easier by not having a public relationship status at all.