I agree with the other poster. WHY would you consider marrying this guy? I love how posts like this start out by saying things are going well, or how wonderful the relationship is.......and then there's always a BUT!
The man has a bad temper, he takes his anger out on YOU when you have nothing to do with his problem, and then gets MORE mad at you because you don't like it.
It sounds like he's got a problem at work, too.....like maybe worrying too much about what other people do. His boss doesn't take action on his complaints, so maybe they aren't valid complaints!
You end by saying "he would never lay a finger on me"........and unless that was in the back of your mind, you wouldn't have said it. Yes, eventually he just MIGHT lay a finger on you.........that's what angry people do. They escalate from plain anger & yelling, to throwing things, breaking things, punching walls, etc..........then the next step is pushing you, slapping you, then punching you.
If I were in your shoes, I would be walking........but at the very least, don't even consider marrying him until and unless he gets some help with anger management. You're right, you should NOT be afraid to TALK to someone you theoretically love, but then, you don't really love someone if you're afraid of them, and you ARE afraid of him. Think long and hard about marrying him, or even staying with him. Things will get worse, NOT better.