Honestly, this sounds more like a r/relationship_advice post than r/homeautomation.
When we installed our cameras (some internal, most external) my wife and I talked about camera placement and what the cameras were monitoring and what we wanted to monitor. We established that bedrooms and bathrooms were no-camera zones and that we wanted to monitor primarily doors and windows. Finally, I made sure that my wife has access to the NVR so she can review the cameras as well (equal access == equal trust). The important bit is communication and information are key for something like this.
Our primary non-security use for the cameras is checking in on the house when we travel or when I want to see if the trash can needs to be pulled from the street. Do you use at-home babysitting? Perhaps that's why he wants an interior camera?
As far as acting silly or whatnot, I don't even really think about the cameras anymore. My wife and I both have walked through the living room in our underwear or less to get something out of the kitchen.
I would highly encourage the two of you to talk through the trust issue that has been found here. Something's not right and if the camera is installed anyways, it could backfire spectacularly and sow discontent between the two of you.
hba card with external ports and a netapp disk shelf? If you get an empty shelf amd poulate it yourself, they are much more affordable.