I'm pretty sure my boyfriend is a strep carrier i've gotten it after kissing many times. he rarely has symptoms and if so very mild. can he be cured?

Normal: Strep is normal in our mouth and nose. The one that causes strep throat and the others exist together (to some degree). To "cure" him would mean removing all the strep strains which is difficult. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2851340/

Yes: He should see his doctor and get strep throat test. However it can only be done when he has sore throat. If the test is positive, he will be treated with oral antibiotics, and the infection will most likely be eradicated. Some people get frequent reinfections because of chronic tonsillitis. There is no recommendations to check for and treat carrier state.