If you smell your feet often, it may still affect your health after a long time. Of course, if your feet are clean, it should not affect your health.
Your boyfriend always smells your feet, which shows that your boyfriend likes you very much and loves you very much. You are also very concerned about his health, which shows that you also like your boyfriend and love him very much. You love each other very much.
If you are worried about his health, wash your feet at any time. (The answer is for reference only)