Can you describe the smell a little more? Is it chemically? Does it smell burnt? Or like something died? Does it smell farty like he didn't flush? Is it sickeningly sweet? Or could this be an ethnic food to which are not accustomed?
I would handle them differently. If it was chemically or burnt, I would act immediately with great urgency. If "poopy" it could be a sewer issue- same with a mildew/mold smell-- all reasons for concern as a host/homeowner.
It sounds like you've started talking, which is great. Maybe see if he can show you where the smell might be coming from? And go from there. If your are polite and he is hostile, you may need to seek support from a 3rd party.