This manga is honestly pretty creepy. Look, if he asked for his new 'job' or something that would be fine, I'm not one to judge, but instead he was basically coerced into it. You can say "well his old job sucked" and it did, but that doesn't automatically make this OK. What about future career prospects? Sometimes working a not-great job for a while can be a stepping stone to something better. The only thing I can really see his new 'job' leading to is a life as a house husband. Which, again, is totally fine if that's what he wants, but he was never even consulted about this. Whatever happened to consent?
300k yen a month is an OK salary but it's not amazing or anything. So while what he's currently doing may be easy he's still not exactly living it up or anything. And the longer he does this the harder time he'll have trying to find any other work. And then there's the fact that the woman herself acts like an overgrown baby. It's just weird.
Let's hypothetically imagine that the genders were reversed for a minute. A well-paid man forces a woman to leave her (admittedly shitty) job and become his caretaker. I think most people would agree that would be pretty fucked up.