I cannot add much to the above, but please realize that detox is not rehab. Detox will happen to anyone who stops using - imagine people that get arrested and are forced to stop using - they will detox.
Your guy had a medically assisted detox, which is good and infinitely more comfortable, but it still isn't rehab. Rehab is typically a minimum of 30 days inpatient and this is where you can learn how to stay sober if you are committed to it. Detox typically teaches you nothing about this, they just treat the withdrawals and make sure you don't die.
Keep us posted, we are here for you.