Interesting hypothesis! In our meta-analysis of household studies, we found elevated risk for spouses. I think there is something special about at least that relationship.
Household transmission of SARS-CoV-2: a systematic review and meta-analysis of secondary attack rate #medRxiv
The overall secondary attack rate with COVID in household contacts is about 20% in a recent meta analysis of over 40 studies. Its higher than SARS or MERS. And less as expected in homes than in small cruise ship cabins.