advice for a teenage girl's relationship?

so, I may be kinda harsh, but my current boyfriend, of 1 year and 3 months, is just kinda annoying. he likes to joke around and says stupid stuff (nothing ever intentially offensive or anything), he's just really silly and I can't deal with it. I ask him to be serious for the most part, or for me at least, and he says "it's hard for him to be serious all the time." basically, he jokes around too much for me and it's very annoying (especially when i'm pmsing or on my period). I don't want him to change himself, but I dont want to put up with silliness all the time, like when I want to be intimate or when we make plans. any advice?