I live with my girlfriend and she was exposed to COVID on Saturday or Sunday (it's the next Saturday now). We didn't know and for two days resumed as normal (kissing, sharing drinks, etc.). She felt sick on Monday and Tuesday but tested positive for the first time Wednesday. We have masked since then and been in separate rooms. Yesterday she stopped masking at home since her five isolation days were up. I'm wondering, if I did not already get it from her (with her viral load or whatever type she may have) in those first few days, could I get it now? Plus, would I then start my 10 days since the last exposure today rather than the Monday/Tuesday I saw her?
A person may continue to be infectious beyond the “five isolation days,” so your girlfriend should continue to wear a well-fitting mask (e.g., KN95 mask) for the next 2 weeks after the isolation period is over. You may have been infected and thus should isolate for a minimum of 5 days and then continue to wear a well-fitting mask when in public spaces for the next 2 weeks.