Uh, no, it's called communication and compromise. You're not telling, you're asking and asserting. Do you ever leave the house?
Um no, it's not compromise in this case, it's called getting your way by saying I won't play if you are using (Insert whatever) sounds like a 4 year old throwing a tantrum. If someone says they're going to use Glass Cannon and I say I prefer them not to and then they don't, then they aren't using what THEY want to use, they're using what I told them to use.
When it comes to this game, I strongly take a stand against builds being made based off what another player suggests. Builds are supposed to be a personal aspect. If a player says hey I have 2 things (A and B) what should they choose, I simply say the pros and cons of each and then tell them to pick whatever one they want that fits their character better.
So... you waste your own time rolling characters and then quitting, instead of communicating beforehand and not only saving the trouble, but possibly convincing your partner to play the way you like if it's not that big of a deal to him.
That doesn't make any sense, why would I roll my character FIRST? Not sure how you missed the part where I stated how one of the first things I ask is what they plan on doing.