Lol, someone with morning sickness shouldn’t be reading this thread, I should know better :).
OP, are you able to pinpoint what type of smell? I have had to deal with this too, its not fun, but depending on the circumstances, you might be helping the person out. Like others have mentioned, anything from diet to medicines to medical conditions to hygienic issues could be the culprit. If there is any way to narrow it down, that might help with the approach. Also, does he live alone or with family/roommates? Is he a teen, young adult, adult?