Here are some of the things that tell me this was not a planned disappearance.
For one, there would be some telltale signs. There might be problems within the marriage, finances, work. There may be behavioral signs as RM would do odd things, out of the ordinary. May it be depression, breakdowns, drug use, withdrawal, or in the matter of another woman, sneaking or being secretive and hiding things. such as phone calls, texts, emails, missing time, etc. By now friends and family would be coming forward to expose such things. Wives with kids who know for certain their husbands left for another woman don't launch a media campaign about their missing husband. They hire a a PI who specializes in finding deadbeat dads.
Now specifically for RM, there are some things to consider pertaining to a planned disappearance. Why would RM go to the trouble of driving to the scrap yard for a small exchange then exit his life boarding a train. Or let's entertain the report that he did go home. He risks getting seen by family and or neighbors, then inexplicably leaves minutes later....to take a train....leaving his beautiful and loved GTO. And why not take his car? It's not like it was marked. He could have drove clear across country and until any cop pulled him over, nobody would be the wiser. Why not just leave work and.....just go? His phone pings in Melville, goes to scrap yard near home.