Boyfriend doesn’t tell me things

I’ve been dating my boyfriend for around 8 months and one of the only things that has always bothered me about him is that he doesn’t tell me about his personal problems or situations that he’s dealing with. When we first started dating I could completely understand, because we were still learning about each other and building trust, but now we’ve been together for a while it’s started to nag at me. I’ve always been with people where we’re completely there for each other and we’d tell each other everything (within reason of course, other peoples business etc. was still kept private), but with him it’s as if he still doesn’t trust me, despite saying that he does. I don’t like secrets in relationships, I believe open communication is the only way they’re ever truly successful, so if he isn’t able to tell me about things like this where they’re affecting his emotions or ability to communicate, I fear that long term it’ll cause problems. It’s kind of a make or break for me.

I only wish to support him, or even just be an ear to vent to if there’s nothing I can do to help. He’s a very private person in general but I hoped he wouldn’t remain that way with me. It makes me feel excluded from his life and harder for me to relate to him, and also makes me feel less inclined to share my problems. I’m unsure of how to handle this, whether to bring it up and explain how I’m feeling or give it a few more months.