With regards to this James situation, I really don't see it being all that potentially complicated. For me, I think his absence could be easily explained.
For starters, when it comes to the issue of "why does nobody seem to know about James?", Stephen not knowing Bella is married isn't necessarily indicative of nobody knowing. He's a guy, and probably not very observant as most guys tend to be, so he's never noticed her wedding ring because his eyes were always looking elsewhere. Jade, however, did know she was married but since she and Bella don't seem to be all that close, she probably doesn't know much, if anything, about Bella's husband or her personal life in general. Furthermore, Bella seems like the kind of person who, until the MC arrived, kept her work and home lives separate from each other, and a result of this would be her work colleagues not knowing much about her and her life outside of work.
As for James's absence, it seems to me that the reason could be a very simple one. In the library scene in Ep 3, Bella's internal monologue is asking for forgiveness from James, seemingly for a past incident where she was "intimate with a friend". Then in Ep 4, if you stay with Bella, her internal monologue now forgives James for doing something. The simplest explanation here, as far as I can guess, is that James cheated on Bella but they didn't separate or divorce, perhaps going to therapy or something like that to work out some issues, but then Bella did the same thing or close to it with a close friend (possibly Jill) and James caught her which caused him to storm out, and they've been separated ever since. Bella still hopes he'll return, and maybe they've been in contact recently trying to sort things out which is why she hopes he'll come home soon.
Just a theory though. She looked to be legit rubbing one out. Clearly she needs to get laid in the worst possible way and only MC's Louisville Slugger will do the trick.
