well i think you need to settle this 'tempermental' issue before you go with him. It sounds like something that could turn into an issue that pulls you two apart, and really should be addressed!
Think about what you said......................."its getting better as long as i keep my mouth shut" Is that how you want to spend your life? Keeping your mouth shut? One thing ive learned over the years..................usually people dont change...........especially if we put up with their bad behavior.