His family is about secrets and power. Growing up with his mom, he's learned that the way to handle things is to tightly control them so no one finds out the ways things have gone wrong. A big part of him is trying to suck Aya away from her more open family and into his, where shame will keep her quiet.
Of course, the other interesting layer is that he hates his family, too. He knows that whole deal sucks, even as he's acting it out now... that's why he's usually so passive (he rightfully resents his awful mom, but he knows it does no good to pick a fight, so he just lies down).
Are we even reading the same story?
Because I have no idea how you reached any of these conclusions.
Yeah, some people on this thread seem to have taken "Kaede doesn't like his sisters" and spun that into HIS FAMILY IS A WEB OF LIES AND MANIPULATION
Guys, his mom visits them regularly, brings them hand-made presents, and worries about their happiness and well being. She didn't get judgemental at all when she found out Ayano kissed a woman, (kinda the opposite, actually,) she just tried to encourage her son's wife to cherish their marriage. She's been nothing but nice this whole time. Yeah, she's probably trying to keep her son's wife from running off with another woman, I mean...Of course she is? She's looking after her son's happiness. She was pushing about children the first time she showed up, but the flashback after that made it pretty clear Wataru wants kids, and Ayano is meh about it, so...again, worrying about her son's happiness. She asked them to contribute financially now that her husband is injured, but they've got medical bills to worry about and her husband is hospitalized, plus she's got an adult daughter that seems to be living off of them. They seem like they're actually in a significant jam, so it's not that weird that she'd go to them for help.
We've seen basically nothing about the sisters, aside from Kaede doesn't particularly like them. This issue showed us that the youngest is a shut-in who loved her grandmother, and the oldest is using her old bedroom as a storage space.
THOSE BITCHES.
Wataru has expressed zero ill will towards his family that I can recall. He was vaguely embarassed by his mom when the family met. Not exactly uncommon. (He also smilingly talked about how she was happy about the marriage, which suggests that he's happy that she's happy.)
I re-read their interactions just to make sure I wasn't missing anything significant, and I can't see anything that suggests Wataru's family isn't just a bunch of pretty normal people.
I agree that we haven’t seen much either way of Wataru’s sisters, but the mom has so far absolutely played the role of a matriarch who suppresses resolution in favor of convenience.
The whole “girls kissing doesn’t even count!” reaction was a great way of invalidating both her son’s and daughter-in-law’s concerns about the relationship they’re in and encouraging them to put the blinders on.
Moving them in primarily seems like her way of more readily micromanaging her kid’s life (and by extension the person who’s a piece of “his life”).