My issue with this young man’s behavior is that there is not one thing that is normal about it. Sure, any given person might respond oddly or badly to some misfortune but there are things that are just way outside the lines.
If the person you intend to marry disappears, vanishes, storms off, or whatever other scenario one could dream up, you might panic. You might be angry enough to say “bleep her”. You might hesitate to sound the alarm for fear it would make you look bad.
You would not just say - welp she’s gone forever, I guess that didn’t work out. You would not pack up your shared vehicle and drive thousands of miles without saying a word about the love of your life dropping off the face of the earth. I simply cannot fathom a scenario where that would be a normal response.
Barbara Thomas’ husband was, quite frankly, super weird following her disappearance. But the first thing he did was the most normal thing. He DID report her missing.
Just my opinion, obviously.