If James is not a soldier, DPC is planting false clues that mean nothing, to confuse people. The biggest one is MC looking under the famous door. What he sees if you look closely, are a pair of military boots. I think DPC doesn't add elements and even little details to the game without a purpose, and those military boots have one, but... who knows?
Maybe DPC actually just made that render for no special reason and James is a traveling salesman and that's why he's not at home. Maybe he's actually a soldier, but he's killed in action or whatever, and the narrative arc of Bella is that at some point we will know that she's delusional thinking that her husband is going to return from death and have hallucinations with him, or something like that, and she will end up the game in a mental institution... But I don't think so, because that would be a crappy ending for Bella's path, not only because it would be overdramatic, but over all, because it would be uninteresting. James' return would be a way more interesting plot twist and offers a lot more narrative possibilities with Bella having to choose between two men, or having to deal with James if it turns out that he becomes violent when realizes that Bella has not waited for him and is fucking a student. A crazy Bella's ending is just a crazy Bella ending up in a mental hospital with Jill and MC bringing her flowers. DPC would disappoint me if his idea for Bella was that.