The easiest way is to put your IoT devices on the guest network and block internet access to the network, but you could do firewall rules if your router allows that.
Or, get a home lab router instead of consumer grade. I went with MikroTik, and it’s a great bang for your buck. It’s not too dissimilar from Cisco in the cli, but the GUI is nice too.
I do the reverse. My IoT devices that I didn’t make myself get shut out of communicating with anything but Home Assistant.
I’ll let them have internet access if there’s a firmware update, but that’s it. Anything that requires an internet connection to work doesn’t get purchased.
It’s not lying. Fat and overweight mean different things in this context. Fat is a pejorative word, carrying a negative connotation. Overweight is a statement of fact
The gf isn’t saying, “I’m fat,” as an acknowledgement of her weight being over the recommended bmi, she’s actually saying, “I’ve gained weight, and I feel ugly and I’m concerned you won’t be attracted to me anymore.”