<human>: Can you give me a shortened version of the text?

Hi everyone. I've been dating my boyfriend for 9 months now, and he's been great - very respectful and level-headed. One of my concerns with him, however, is his road rage. He's very polite and agreeable, perhaps more so than the average person. However, when he gets on the road, suddenly everything makes him angry. A person up ahead doesn't signal that he's changing lanes (but does not cut anyone off)? Rage. Cars on the freeway who don't use the left lane as a passing lane? Rage. Bumpy, ill-kept road? Rage. Pothole? Oh, all the frightening rage.

He gets so angry in the car sometimes that it just makes me want to sink into my seat and disappear. It's very uncomfortable seeing someone you care about so much be so angry, especially when he is so polite and mild-mannered outside of a car.

He's explained it to me by saying that inefficiencies (in traffic, video games, programs, anything) piss him off, as do people who increase the likelihood of accidents. But most of the things he gets angry about are not dangerous, such as a car up ahead changing lanes without signaling when our car is the only other car for miles.

I wish that I could help him stop being angry on the road because I figure anyone's lifetime utility would be increased by decreasing unnecessary anger. However, I can't figure out how to make him care less about small mistakes drivers make on the road everyday, if it's even possible.
<bot>: Boyfriend has road rage over mildly harmless mistakes drivers make on the road everyday. How can I lessen his anger, if possible?