I think the longer the relationship existed during active use/drinking, the less likely it will survive sobriety. I had a 15 year relationship that ended in 2006, met my current GF in Sept 2009, went into rehab Dec 2009 and we (new GF & I) are doing really well.
I don't know that it would have been possible to overcome the years of neglect that I inflicted on the earlier relationship. I was never abusive, but alcohol was my first love/priority and though we still stay in touch and did separate very amicably, I suspect that I had poisoned the well of our relationship beyond repair.
I have a question that relates to this - will post in a separate thread so as not to hijack...