Boyfriend texts female "friends"

So my boyfriend has several female friends that he never sees in person, nor have I ever met. He will go a few months without texting them sometimes and other times they will text 50x a day morning, noon and nite. God forbid I ever say anything or he flips out. I can't see the messages and if I asked to look at his phone or did it would be the end of the world type of screaming argument. I do know the password to his phone but if I used it would be a big deal to him. Oh and he texts one of them in Spanish and I don't speak or obviously read espanol. And it's the same friend he met on a dating website a few years before I met him. Would this bother you??? How do I tell him it bothers me? Is it wrong it does?? Thanks...