Ever dated someone who acts like a giant toddler when they're told they can't just do whatever they want? Redditor u/throwawaycakegf 's girlfriend is a perfect example of what I'm talking about. u/throwawaycakegf recently posted to r/AmItheAsshole after getting into an ongoing argument with his girlfriend over some cake mix. In his post, OP explains that he was helping his baker sister with her business by making wedding cake mix at home so she wouldn't have so much to do in the shop. He notice…