It's not appropriate to assign your feelings of hurt to your boyfriend's actions. The two are related, but not causal.
Let me give another example: I could say "the bank is hurting me by not letting me withdraw more than my balance from the ATM". And, it could be true that I might wind up hurt if I can't get the money (shouldn't have spent all that time in Atlantic City talking smack about the Mob). Still, ultimately, it's up to ME to resolve my own hurts, potential or realized.
That said, it's imperative that you do share your feelings. But do try to find a way to do it that doesn't make YOUR hurt your BOYFRIEND'S fault, or that forces an ultimatum or compromise with his other relationships.
If you're the studious type, it may pay dividends to read up on, in order to best ascribe your feelings to yourself in a way that will best encourage your boyfriend to listen to, understand, and even empathize with your point of view.
Another good "shorthand" for tying your feelings back to yourself is to write out how you feel using, which is a form of English that eliminates all forms of the verb "to be". For example, the E-Prime version of your question might read something like:
- How do I tell my boyfriend I feel uncomfortable, lonely, and/or jealous of his friendship with certain girls?
Simply put, don't try to exert control over others -instead, listen to yourself, and express yourself fully as a means to achieving good self-awareness and self-control. If your boyfriend doesn't understand or won't listen, then re-evaluate the longterm potential of the relationship.