Might be. But either he left or she kicked him out after something he did happened and she says that she has forgiven him for whatever and is waiting for him to come back. This conjuction of logic is weird.
That's a big bet, mate.
The adulterer part of her monologue in MC's room in the DIK mansion is detail and gives us some insight. She hates adulterers. She says she became what she hated. I find it weird that she'd just forgive James if he cheated on her, judging by her personality.
And as for the asset thing, I find it weird. Especially DPC who is obsessed with little details, to leave that thing there with no purpose is pretty uncharacteristic of him. Either it's some weird fetish or it's for the child. Though, even if the child used the stool for the bigger mirror, I don't think it'd reach that height.
I don't necessarily think it's James' fault. Besides, if it was, I don't think Bella would ever forgive him for that. Now that is a huge tragedy and it would probably create a huge rift in their relationship.
I think she miscarried or something and the trauma such a thing causes, caused them to drift apart. Then James' gave himself to alcohol to numb the pain, cheated on her, got caught and promptly kicked out.
If we are to go in
dalli_x land of theorycrafting, James cheated on Bella with Nicole, got caught and kicked out, knocked up Nicole, but then left her and now his current whereabouts are unknown.