If you are performing oral sex then if he wears a condom your saliva, if it has active virus and comes in contact with any mucosal area not covered by the condom - you could. If he is using a condom and you have traditional sex then I would still be careful to not engage with a partner if there is even a suggestion of active viral disease. I would also consider taking an anti-viral like acyclovir if you are commiting to lysine since the studies do show that an anti-viral can reduce the viral load and reduce recurrences.