I myself went otd from age 18 till 30. I agree that the unconditional love is most important. I can remember coming home 2 am Friday night by cab and no one said a word about it.
I apologized to my mother once about this and she said, your’e my son you are always welcome here.
this made a very strong impression on me possible the thing that kept the connection. I always said SHma at night and went to Shule on every Yom Kippur except one. SO see if you’re son wants a minimal connection like that and be proud of that.
I think tho that nothing was going to keep me away from the otd.
in my case there had been molestation that was never dealt with and also some other trauma.
SO don’t try that much to keep that road off closed they are going anyway but keep the light on.
also in my case, learning Torah was the spark back not davening.