My boyfriend has mono even though hes a germaphobe and only shares stuff with/kisses me. i dont have mono and i took a test 3 days after his diagnosis and i tested negative. where would he have gotten it from & why dont i have it if i kiss him?

The primary cause of mono is a rather stealth virus that can cause illness days to weeks after exposure/germ transfer. In many there is no obvious source. Your negative teat at three days may mean you had it as a young kid when it is often very mild and no different from a simple virus. You could be immune or in a few weeks you may develop the disease.