Your friend has given you the same advice that we have. It't all about him and his issues and that you had absolutely nothing to do w/them. Turn the matter over to God and allow him to work on him.
You may not hear from him again for many weeks, even months. Some just disappear for long periods of time. It's nothing to worry about. They are just out there doing their own thing and the euphoria of a new adventure has their focus right now. You don't see cycling until further along the path, if he's in MLC.
I don't recall a thread on the ow that we have ever posted here. We speak of her as being nothing more than a Band-Aid and usually she has issues herself. They enjoy each other's company and she is most likely a f@ck buddy to him. The feelings of love are not he same, i.e., it's more like friends/companions. Somewhat like friends w/benefits. Mlcers are looking for something new and exciting and usually very different from us. Eventually the newness will wear off and the old routine will come into play.
We all have learned to cope w/the lack of contact by focusing on the day-to-day activities, getting involved in projects and hobbies and if there are children...you focus on them. The first few months will be the hardest, but if you can look to each hour versus day, you'll be okay. Find things to keep you busy, hook up w/old friends and I always encourage people to make a list of the things you've put on the back burner as well as new things and get started checking them off the list.
Keep in mind, this is a very long trip and there are no guarantees that he'll want to reconcile w/you. You need to act as if he may never return and move forward w/your life. Life is far too short to sit around waiting for him. Life is waiting to embrace you, so open yourself up to new adventures and if, and when, he contacts you, you'll be in a better place, a place that you will feel much like your old self and who knows...maybe in an even happier place. Please don't put your life on hold for him. Live your life to the fullest.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.