hi embrace. That's a tough one. Have your broached the subject with her at all? I mean as in actually coming out and asking why she is being so distant?
She could be trying to adjust to being a sober person, she may have felt "forced" in to rehab and is unhappy about that, she may have met someone in rehab, she may just feel different now because you two have basically been apart for months.
Do you have a gut feeling about this at all?
Personally, I would talk to her, tell her what you are experiencing and ask her what's going on.