I do not think you failed at all...I think sometimes things like this look bad...but then time passes and bang the kid straightens up..My mom and dad were like very Walton like ...no way could I have moved a guy in no matter what was up but I drank and did drugs...Scary as it sounds Sleeps won a scholarship went to college..drank there too but did graduate with high honors and just didn't do drugs much or drink again ..SHE became a professional student ...In fact I do not drink ALL ALL now...I pretty much behaved as my mom would say..Sometimes we have to be our own person and pay for our mistakes...have rules that are firmly set and followed and ..then we make or break ourselves. It may help to say his GF WILL go if he does this stuff again and THEN STICK TO IT...My mom and dad could have followed me around 24 -7 fought or begged me to knock it off I would not have listened to them..So they had rules and I suffered when I got caught breaking them. I wasn't caught often .. Anyhow youre a good mom I think it aways comes back to being a bit more firm and consistent