It doesn't mean he cheated on you. However, you don't say what type you have (1 or 2). You could have contracted it through oral sex (cold sore on his mouth to your vagina) or through penis-vagina sex (type 2).
first outbreak is often the
worst for folks. I had my initial outbreak years ago, the
n never had anothe
r one and never had any symptoms after that. It varies from person to person. Your boyfriend needs to get tested, obviously, so you two can figure out which types you have.