Dear Fay1, I'm so sorry to hear that you and the friends and family of the friend you mentioned are going through so much worry.

From the information you provided, it does seem that your friend left with no goodbye purposely. If his family or his girlfriend has enough info. to access his banking information, you might be able to get some info. this way. (But you have probably already thought of that.)

I had a close friend disappear once similarly, but he did have a history of mental health problems. He turned up after a few weeks, but his children and friends were worried sick in the meantime.

I hope that he will get in contact soon.