So if me and my bf both have like herpes on our lips and he still has a slight cold sore but mine just healed. could i kiss him or would i get another cold sore the day after?

Basics: Cold sores are caused by 2 strains of the herpes simplex virus. If you both have the same strain, you cannot pass the same strain back & forth like a strep throat. It might be possible if the strains differ, but it is most likely they are identical. Cold sores erupt when the virus re-activates in the tissues. Once you have the strain in your system it remains indefinitely.