Sounds like the kid got dealt a shit hand, and I don't know what would be worse: being a system kid or being raised by people who only took you in out of familial obligation and one of your new "parents" hates you for existing. If I had to guess, the married couple in question were already content with their family size (whether it had kids in or not) and that's why the husband was upset about the introduction of another family member.
Why can't the adoptive mother handle him anymore? Does he have behavioral problems? Given his bio mother abandoned him and his grandparents died or became unable to care for him, I would be more surprised if he
wasn't fucked in the head in some way or another.
This woman should have never taken this kid in. Sounds like she did it without consulting her husband beforehand, or she did and just disregarded his opinion and brought the sprog home anyway. Her marriage was already on the rocks, so why the fuck did she bring a kid home? Children have never saved troubled marriages. She says she won't leave her husband, but who is to say
he won't leave
her? They weren't getting along to begin with and then she brings a brat home whom he doesn't get along with either. He has nothing to lose and everything to gain by packing a bag and walking right out the door. Not necessarilygetting divorced, but just leaving. Let Moo deal with the kid herself, whether it's raising him or rehoming him.
I don't think there's any shame in admitting you can't give a child the attention they need, but she should have thought about this shit BEFORE bringing the kid home. If she winds up having to give him up, it'll be nothing but yet another parent who didn't want him and he'll probably develop reactive attachment disorder if he hasn't already.